Many people slog all the way through any book they begin. My eyes pop out at them.
Some people will read 50 pages then decide. Why suffer?
There are variations galore. For a book by a new author I'm considering, I read the jacket flap and back and read the first page to get a feel for the writing style, the character and the interest level.
The book has no shot with me if:
1. It is written in first person present tense. Gawd. So pretentious and jarring. "I walk down the hall and smell the bacon. It transports my nostrils to another time and place."
2. The book opens with alot of boring description of a place or person. Let's jump into the action!
3. The characters are immediately unlikeable : whiny, smarmy, prissy, dark evil serial killers (see how these all go together.)
4. The book is badly written and just goes blah blah blah from the first line. Zzzzzzzzzz........
5. The book is part of a series I've enjoyed but clearly the author has long since tired of the character and series and it shows.