As a bibliophile of 45 years, I've read a lot of books, both good/great and awful.
I've also developed a list of pet peeves that make my blood pressure go up and rouse my ire, as I am certain they do other readers and bibliophiles.
These are in no particular order of irritation, they just all annoy me.
1) Cliches and stereotypes: DO NOT USE THEM--EVER. Yes, I know there is a reason they exist, and that there are often kernels of truth buried within them, but I still think you don't need them if you've got any kind of imagination or talent as a writer. Really, folks, bosoms do not heave, "manliness" doesn't throb, and all fat people don't eat junk food all day and never exercise because they had bad parents or a traumatic incident with a relative. There is no reason why paranormal romance authors, or urban fantasy authors or science fiction/romance hybrid authors can't use the word "penis" or the word "vagina" for that matter. Also, if you're not going to write horrible racist stereotypes, such as all African Americans liking to eat fried chicken, collard greens and watermelon, then why would you need to stereotype the 62 percent of the population that is overweight, particularly the women? There are as many reasons why people are overweight and/or obese as there are people. My situation is different than my friends who are obese, because we have lead different lives, have different diseases and are working on our health in different ways. I exercise 6 days a week, for 7-8 hours a week, and I am still obese, yet I can't really eat junk food, because it usually makes me ill (I have Crohn's Disease). I have friends who are obese who eat fruits and vegetables and whole grains and wouldn't touch sugar or processed foods. And I know a number of women who are overweight who had wonderful childhoods, great parents and are mentally healthy. Authors, don't take the easy route with cliches and stereotypes--be original and realistic in creating your characters.
2) Plagiarizing other authors/"updating" classic works or themes in literature.
Ray Bradbury wrote a wonderful short story about a group of vampires who had banded together as a family and who lived out in the wilderness of a part of the US that didn't get much sun. A "teenage" vampire in this family falls for a mortal girl, and problems ensue. Sound familiar, Twilight fans? It should, as I believe Stephanie Meyer took Bradbury's short fiction and added her own horrible prose and vile protagonist (the whining, idiotic and personality-free Bella) and created a syrupy romance phenomenon. Now there are a whole slew of Young Adult fiction authors who are writing vampire romance novels because they want to hop on the Twilight bandwagon and make money, shudder. How terribly trite and boring and what a waste of ink and paper! Unless you have some extremely unique and imaginative take on Bram Stoker's Vlad Tepes/Dracula story, don't bother. Granted, there are some authors who, previous to Meyer's drivel, actually did just that, and created vampire characters that we can read with fascination. Robin McKinley springs to mind, or Jim Butchers vampires in the Dresden File books. Ann Rice brought back Gothic fiction from the grave with her "Interview with a Vampire" series. Even Chelsea Quinn Yarboro's St Germain series has a unique take on the vampire legend.
But did we really need vampires that are "pretty" and don't go out in the sun because they "sparkle"? The short answer is HELL NO.
Hollywood has been especially pathetic in 'updating' classic novels and films lately, as if the dearth of creativity and original ideas has become a void. Sadly, most of the "updates" stink, and there are young people watching them who probably haven't seen the originals, and don't realize that this was once a great tale well told.
3)Complex technical jargon/languages other than English that remain untranslated. Seriously, if it doesn't move the plot along or illuminate something important about our hero or heroine, leave it out, please. I don't care about the fictional math equation needed to get the hovercraft or alien airplane off the ground, or make if maneuver around the planets, or fold space, or whatever other gee-whiz things it can do. All that tech stuff is BORING to regular readers, who make up the bulk of people purchasing/reading your novels. It doesn't make you appear smarter as an author, it just makes you seem like more of a snobbish geek who is unwilling to allow the rest of us to read and enjoy your work of fiction, which is supposed to be entertaining. If I wanted to learn quantum physics, I'd go back to college. Don't torture your readers.
I don't think I will ever forgive Umberto Eco for putting an entire page of Latin in "The Name of The Rose" that remained untranslated. How rude at best, and cruel at worst. There just are not that many people who had Latin classes in high school or college anymore, and a majority of readers had no way to translate that page. Don't make me want to smack you when I meet you at a book signing. Leave off the technical stuff and translate any language but English, please.
4)Introducing characters that disappear without a trace
I just finished another Richard Russo novel (for my library book group) and once again, I was astonished that the man continues to be published and lionized as a man who creates great 'literature.' His 'comedy' novel "Straight Man" wasn't even slightly amusing, his novel "Empire Falls" needed a good editor, and "Bridge of Sighs" was full of characters I despised, including one gal, Nan Beverly, who is given short shrift in the book as the 'prettiest girl' in the local high school who gets busy with the local Lothario and then we never hear what happened to her. She just disappears amidst a cloud of speculation on whether or not she was pregnant and shipped off to Europe. There have been numerous novels coming out in the past 10 years, written by authors who seem to think that it's just fine to do this, create a character and then make them disappear when they're no longer needed. This will only hack off your readers, trust me.
5) Long narrations that do nothing but stall the plot/details that don't enlighten or inform
I reviewed a paranormal romance awhile back that had a whole page devoted to a scene in which the male protagonist drank a soda and then meticulously searched for a place to throw the can or bottle away, because he didn't want to litter, he likes to recycle his soda cans/bottles. Whoo-hoo...wake me when it's over, will you? Why the author chose to bore the reader with these details that have no reason for existing, I don't know. There was no reference to this character recycling, or his love of soda, or anything else later in the novel. It was just 'padding,' I suspect, to make sure the novel was the appropriate length for publication, and the author didn't have the creative mojo to do any better. I've also read an SF novel recently that had long-winded narrations about political situations and academics that were so boring, they were great antidotes to insomnia. I think authors forget that "show, don't tell" admonition, and they also forget that action is preferable to narration. Keep that plot moving and those characters flowing along, please, lest your readers give up on your novel and use it as a doorstop.
6) Bad endings or none at all
Modern fiction, I've discovered, is rife with authors who haven't a clue how to end a novel. So they don't, they just leave the reader hanging, filled with that unsatisfied feeling of having had your plate removed from the table before you were finished with your dinner. Though I am a fan of HEA, or Happily Ever After endings, I don't insist on them because I know that genre writers who create long series of novels often don't have the luxury of having a complete HEA, unless they've decided to kill off their main character and move on to another series. But if you are not writing a series, please, I beg you, tie up the loose ends, tell you readers what happened to old Aunt Maude, or at least kill her off so we have some closure. I'm still a tad miffed that I have to wait a year to find out if Harry Dresden, Chicago's finest wizard, is dead, because Jim Butcher chose to have Harry get shot at the end of the last novel and fall into the water. Nice cliffhanger, Jim...not.
7) Mistaken genres
I read a lot of authors who are crossing genres, and while that's fine, it's annoying that publishing companies don't have more of a handle on the main genre or category to place them in so the readers can find their works. Linnea Sinclair's novels, for example, are SF/Romance hybrids, but are not always shelved in the Science Fiction section of the bookstore or library. Often, she's relegated to the 'pink ghetto' of Romance fiction or even 'chick lit,' which is certainly far afield from what she's writing about.
8) Novels without humor/wit
There are way too many authors who assume that funny equates with making fun of people in a cruel way, or using stereotypes in an ugly fashion. That's not funny, and having witty dialog between characters seems a thing of the past. A novel without humor, or at least an amusing insight or two, is like a fish left too long in the sun, it stinks.
Master of Comedy Stephen Fry could remedy this situation by creating classes on wit and how to use it. He could literally save the publishing industry single-handed.
9) Vile, evil and stupid characters
I realize every novel needs a black hat to compete with the white hat of the hero, and I'm fine with that. But why oh why so many authors feel the need to fill their novels with stupid, evil, vile characters with no redeemable qualities, I do not know. I think I speak for the vast majority of readers when I say that we need someone to root for, someone we can identify with and understand enough to want to take the journey through the novel with them. Most readers don't see themselves as vile and evil people, and want to see themselves, or parts of themselves, reflected in the characters of the novel. If all you have are people not worth writing about, doing awful things and not paying the price for those transgressions, why bother writing a novel at all? You will only bore and disgust your readers. I don't care about people who are a waste of oxygen, I care about characters who learn, grow, do great things or try to do great things and who care about morals, values, character. I read to be enlightened, entertained, informed, uplifted by good storytelling, not depressed by sordid characters doing unspeakable things to each other.
10) Novels that are in dire need of an editor and a proofreader.
This would include at least half of the novels I've read in the past 10 years. Even the wonderful JK Rowling and her delightful Harry Potter series got seriously bogged down in the last book, so much so that I was with a group of bibliovores one day and every one of us complained about the same part of book 7, "The Deathly Hallows" because we all felt like the scenes with Harry hiding in the woods were too long and could have been cut without harming the book at all--in fact, taking 200 pages out of the book would have made it a better work of fiction.
I know that I'm not the only person to notice that in the last 25 years, as publishers go out of business, newspapers and magazines fail, that the quality of prose being produced has taken a significant nose dive. There are now typos and grammatical errors in almost every book you read. Some of these errors are so blatant, I find it hard to believe that the author didn't catch them. Still, it is the publisher who needs to hire more proofreaders/copy editors and set them to the task of cleaning up manuscripts that are riddled with errors. Don't make your more literate readers want to gouge their eyes out by the end of the novel, please.
One last thing, there is no real need to use curse words or filthy language in every paragraph of a novel. My late friend Rosemarie Larson used to say that only ignorant people with no imagination swore and cursed, because they couldn't think of better words to use. Will Smith said his grandmother raised him to believe that as well. Be clean, be creative in your use of the English language.