I used to always push through every book I started. Then I realized life is too short to waste on books I really dislike. But I have to REALLY dislike a book to not finish it. I think there was actually a book I once threw away and did not even donate it to the local library book sale because I disliked it so much.
I usually tell myself that I broadened my horizons by finishing the book but would never choose to read anything else by that author.