Books at bedtime

Our little stinker is definitely getting very picky about her books at bedtime and we can't figure out what it is that makes her like or dislike a particular book. Is it the colors? the characters? rhymes? song books? She seems to know before we even read the first word if she wants to read the book or not; we open a book, and if she doesn't want it she immediately closes it and tries to throw it to the ground. This is a lady with an opinion no doubt. There are some books I feel silly reading later by myself because I wanted to see what they were about! Nerd alert: I keep an Excel spreadsheet of books to use later in my classroom, so having a small child to read to for these years I'm a stay at home mom will greatly help my teaching some day when I go back.