I judge books by their covers. I know I shouldn't but I do, but after i judge them worthy enough to be picked up, I jump to the middle of the book and read an excerpt of description, flip a few pages, and then an excerpt of dialogue. If you pass both, I will buy you. I do not read the beginning of the book to pull me, because as you and I both know, many authors spend most of their time trying t work up a good beginning and then fail! They suck after the first some odd pages.
I almost forgot to say why I judge by cover. I always say to my friends. The best authors get the best artists. Not always 100% true, but it has yet to proven that I am completely wrong. For the most part, it is right, from what I have read.