Colbert judges you first.

This site gives you a cover, makes you rate it, then compares it to the median rating on Amazon. 

Outstanding. To think, I've been doing that for years for money when I could be doing it for free. And what's more, with no reasoning other than "ooh! shiny!" and "ugh. not shiny." Might as well try it with a method that's closer to  "scientific." Or hell, even something closer to "logic" and "sound."

G'head. Judge a book by its cover.