What ruins a book for me:
- The obvious stuff--poor grammar, misspellings, etc.
- Endings that feel like the author just finished a community college "Intro to Psych" class (see: In the Woods)
- Adventure without character development or character development without adventure
- Any sex or violence (or any other behavior, really) that doesn't affect the plot or develop the character--stop telling me that they brushed their teeth unless it's telling me something about them that I need to know
- Violent, dehumanizing sexual activity (see: Bret Easton Ellis)
- Dehumanizing violence (see: Thomas Harris) - though some dehumanizing violence serves a plot or narrative that ultimately works to humanize the characters
- A character who never has a wrong intuition or a bad idea (I'm looking at you Mitch Rapp)
- Blatant political soapboxing
- When the author treats me like I'm stupid