There are quite a few things I can't tolerate in books:
- Purple prose. It ticks me off more than anything.
- When writers use words without looking up their meaning / rape the thesaurus. For instance, Stephenie Meyer and the word "chagrin" among others.
- Second-person narration gone wrong. Most of the time, it is contrived in novels. Some writers do take the time to make it as good as first-/third-person narration.
- Mary Sue/Gary Stu. I loathe flat characters, characters who have no flaws, and self-inserts. It makes me feel like I'm reading a story on fanfiction[dot]net rather than a published book.
- Grammatical errors/spelling errors. Because if I wanted to read the unedited version, I would have googled the manuscript.
- Too much telling and not enough showing or contradictions in the show and tell aspects. If a character is smart, then at least have the character have an intelligent thought. What good is the writer telling me that the character is a genius if everything in the book contradicts that?