I actually do have a criteria. The very first thing is, if it is good enough for me to download it, that's automatically good for 3 stars. If the artist in me says, 'oooo, how'd they do that?', that's good for another star. Then if my initial reaction is 'This is the best dang (insert skin type here) I've ever seen!' then that's a five star. I don't generally rate skins I don't like, unless I think it's really bad and not even worthy of being on the site... then, I rate it 1 star instead of making a bad comment.