Okay, Let's get started:
Most of the Classical Victorian shit -- your Brontes, your Austens, and everything in that general category. I had to read it for school, and I just hate, hate, hated it. Dry, boring, pedantic, completely unappealing. Pretty much anything written in English between Shakespeare and Tolkien is a complete anathema to me.
F. Scott Fitzgerald -- just can't The Great Gatsby, haven't tried reading anything else.
Stephen King -- loved On Writing, think he's an amazing and creepy dude, just can't get into his prose.
Kathy Reichs -- kind of the same thing. I love the TV show BONES, but her books never hooked me. I even tried her Young Adult series, and it didn't click.
The Existentialists -- Jesus Friggin' Christ, man. Seriously.
A lot of the Indie/Self-Pub YA and NA books you see these days -- some of it was so terrible. I read this one book at my sister's suggestion, it was low quality, pretty sure it was POD, unedited, and the body of the text was type-set in a sans-serif font, Arial, if I remember correctly and trust my eye. I've tried reading it on occasion, and most of the time, it's been a proven waste of my $0.99
James Patterson -- He wrote the Maximum Ride series, right? I actually kind of enjoyed the story, but the writing was tedious.
James Frey, AKA Pittacus Lore -- I started reading The Lorien Legacies, despite the blatant Tolkien rip-off. I liked the premise, but damn it if the writing didn't get worse and worse.
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I have to say, I'm surprised by all the negativity toward GRRM -- I'm not one for a great deal of sex and violence and blood, but I really did enjoy the books, though I'll admit, I did watch the first few episodes before I picked up the books, just to get through the "who the f--k are all these people?" stage. (I literally went onto my tumblr, wrote down descriptions of the people ["Boromir, Boromir's Wife, Fat King, B--chy Queen, Ken-doll knight"] and had my friends make me a character reference list).
But once I got in, I was hooked. I especially enjoyed Daenerys and Tyrion's stories once they got going. But to each their own, I suppose