(Lol, I started to write a post for this back in July 2015, but I never finished it. x3 I think what I was writing was just devolving into a rant, so I gave up...I think it still turned out like a rant anyway. xD Oh well...)
Books you should never read? 50 Shades of Gray. I opened it to a random page and was scarred immediately.
That doesn't surprise me. I think I was scarred reading the book summary on wikipedia. XD (In fact, there's an entire genre of 'erotic romances,' and what's more, specifically S&M-type erotic romances. This is part of why I've come to think books ought to be rated the same way movies and fanfiction on ffnet are rated, with brief summaries explaining what the ratings are for, because you have to be really careful, or you might end up picking one of these books up by accident. They're usually marked, but sometimes you're innocent enough you don't realize these things exist, and aren't on the watch for them. X3)
Another book that was getting a lot of attention for awhile was Gone Girl. (Well, it was at the time I was first writing this post a year ago, lol.) I never read it, because I thought it looked too dark for me (I read a plot summary on wikipedia out of curiosity though), but my sister and some of her friends, because they'd had so many people recommend the movie to them, watched the movie, and even though they're pretty used to dark psychological thrillers, they were absolutely shocked at some of the content. So that might be another one to be wary of.
As for books I've actually read—to be honest, it's very rare that I read a book that I have a really negative reaction to, mainly because I try to be careful what I read. (I mostly choose from the tween/teen genre to avoid certain content, or I skim book summaries online ahead of time to try to get a feel for what kind of book it is. I can usually tell when a book has content that I don't want to read, and so I just choose not to read it, or else I have my mental defenses up, so I can just breeze through those things I don't care for without having a serious reaction.)
But, there have been at least a couple that have sneaked past my guard in recent memory.
First is State of Wonder—someone came into the bookstore I work at asking for this book (because she'd already read most of it, but lost it, and she only had a little bit left of the book to read, and she wanted to know the ending.) We didn't have it, but when she described the plot I thought it sounded interesting, so I wrote down the title and decided to check it out from the library.
Most of the book is fine, but the ending was so bad, it was almost unreal. (If only I could go back in time, I would tell that customer not to read the last ten pages. Because the book would have been so much better with the end chopped off.) The ending completely violated the integrity of the characters—they betrayed the people they cared about. (Yet it was never addressed as a betrayal—life just went on as normal. It as almost like, 'We've been through so many horrible things through the course of this book, we deserve this.') Which is something I just couldn't stand.
Second one is The Song Master, by Orson Scott Card. The Ender's Game series (also by Card) is one of my favorite series of all time, and the complexity of the characters and the world he slowly weaves has been one of inspirations for my own writing. When I decided I would go back and read some other books he had written, and I got to this one, I wasn't simply disappointed, I was appalled—not only is much of the content disturbing (the sense of the prevalence of pedophilia creates a picture of the world that turns the stomach, not to mention there was an unsettling scene where the main character's teacher attempts to 'break' him through psychologically cruel means, and as far as I can remember, it comes out in the end that it was due to a misunderstanding, rather than a really necessary part of his training. A man who treats others with cruelty [one scene in particular, involving his callous and appalling treatment of a prostitute sent to him by an enemy to distract him, really made an unpleasant impression on me] is later praised as a great leader.), but also, in the course of the story, my feeling was that the main character becomes overpowered, in the fanfiction manner of mary sues and gary stus. He's already a genius when it comes to the power of song, and this control over his singing grants him particular powers, but later on he is kidnapped by people wanting to assassinate the king he is working for, and in the course of that, he becomes a kind of super-ninja killer, and doubles as a bodyguard for the kind, as well as his 'song bird.'
Partway through the book, I went online to read a summary of the rest of the book, to see if it was worth reading, and when I saw how twisted things get, I decided there was no point going any further.
So, I highly recommend the Ender's Game series, but I would stay away from that one. (And in Card's defense, it was one of her earlier works, it's hard to say how long he had been writing at that point, and how much experience he had.)
Anyway, I don't particularly like to be negative about books, as everyone has their own tastes and interests, and they have the right to read what they like. But these are a couple I just really had bad experiences with. x3