What keeps you reading beyond the first few pages of a book, and what makes you stop reading a book and put it back on the shelf?
I'm pretty forgiving when it comes to books. Even ones that don't totally suck me in will still pull me through the pages, but they won't keep me up reading late into the night. I can put them down, walk away, come back sometime later when I feel like it. Only curiosity to know how it turns out makes me keep reading. I just don't read those ones again or often. The ones I sacrifice sleep for have brilliant writing and characters that grab me.
Ones that do make me put them down, assuming I picked them up in the first place. Excessive unreasonable violence, MCs doing things I cannot root for and antagonists who are just as bad (stories from the villain's view where I can root for the antagonist aka hero are different), excessive swearing, a sequence of events I cannot find at all plausible in the context of the world setting, a total snooze fest, or very confusing.