I have thrown down a lot of books lately already when reaching around page 10. These includes Steinbeck, Sue Grafton and others. Here's a few reasons, and tips of what not to do.
1. Don't Preach.
Unless, of course, your character goes around preaching to everyone around them. Then it's your character preaching, not you.
(There's also a difference between Preaching and Having a Meaning. It's the difference between a blaring headline saying STARVING CHILDREN IN UGANDA and the black and white picture with the skeleton-thin baby looking blankly out into the desert)
2. Don't POV shift.
Alright, if you're writing Harlequin, you can POV shift in the middle of a scene. I only read those for the historical swoons and the similes such as "the motorcycle felt like one gigantic d***do".
3. Don't close me out.
If you're putting the reader some distance away from the reader, you lost me already.
4. Don't use cardboard characters.
If you can replace the characters' names with The Incurable Bachelor, the Promiscuous Bitch, the Shy and Secretive Professor, you're probably guilty.
5. Don't puke out characters on me
Unless your POV character is... wait, scrap that. There's never a reason to take up several, or even one, paragraph describing exactly how a character looks, what they like doing, what they've worked with and how their childhood was. Not the main character, not the other characters. I read to get to know them. Start with this, and I don't need to finish the book. In fact, I can just scan the first few pages in the bookshop and not buy it at all.
6. Don't lose track
If you've already have one character suspecting your character of something, don't make a big scene of him being all shocked when suspecting this later (and again!). Also, don't have your character reading the name on her borrowed suit, if she'll seconds later will wear her own spare suit. That just proves you aren't making an effort (get yourself a good editor/beta reader).
7. Don't make everyone gorgeous
Alright, I do this myself. But it's annoying when I read it. *vouching to stop*
8. Don't write a genre I don't like
Hey, I said it was about me. This is just a reminder that everything is about personal taste - if I don't like your book, it might not be about you after all. Though a damn good book makes me read any genre.
9. Hide my cookies
I like my sweets, but if you're going to drown me in every bit of the character's personality up front, I'll have nothing to look forward to. Dangle them ahead! Make me wonder "why did he say/do that?"
Alright, can't think of more Deadly Writing Sins. Feel free to add some yourselves through the comment section!