Can you REALLY judge a book by its cover?

I like This Little Post From The Marginal Revolution blog: “I saw this and thought I should buy the book — Kate Christensen’s novel The Great Man — just because I liked the cover. As an experiment, I deliberately did not scan the contents or read the blurbs on the back. The title isn’t very descriptive either. I then bought the book.

My thought was this: presumably the publisher designs the cover to appeal to people who will spread favorable word of mouth about the book.”