Good judgement.
Good cover.
Good book.

The book was A PRAYER FOR OWEN MEANY by John Irving. I found it in a thrift store. I put it on a bookshelf and forgot about it. Then a couple years later I noticed another cool book cover at a yard sale. I bought that book and was putting it on the bookshelf and realized it was the same title as my thrift store find. I assumed the universe wanted me to read it and so I began.
I loaned a copy to my sister and we would discuss what we had read from time to time. I realized that I actually loved the characters and the story so much that I slowed the process of reading it down so that it would last longer. Sometimes I would reread chapters so that the story would not come to an end. It finally did,... a year later.
The 1998 feature-length film "Simon Birch", directed by Mark Steven Johnson, was loosely based on the novel. That was a terrible movie. I'd have to say it may be better to judge a book by it's cover than to judge a book by it's movie.