Judging a book by its cover

How do you pick books to read when you want to read something new?

Usually even when I know I need only a certain book I end up lost in the bookstore for a whole day looking at the different categories to see if some title catches my eye I usually end up buying tons of books I will probably never ever read and spending way too much money...some people do that on clothes, I do it on books and music or movies usually

Anyway usually I first fall for some title, then read the plot on the back of the book...the cover might capture my eye too but if I dont find the summary interesting usually I leave the book on its shelf.

What about you? what criteria do you follow to pick random books? do you judge them just by the cover or you consider other factors too?