Also it actually cuts down on bad posts, if people notice their bad shade isn't getting any likes, they'll stop doing it much faster than realizing they're never getting quoted.
I think adding a like button alone is an OK idea. I know PMB is pretty much a smaller scale version of ATRL, they have a like button, and it's not nearly as messy as this place is. I'm not saying it's correlated, but I don't think it causes problems like some are trying to say. If anything, it cuts down on quote spam/stops wouldbe flamebaiters when their posts get paid dust.
I wouldn't care for one as it's not hard just commenting. Chances are, too, that the person 'liking' or 'disliking' a post/thread will more than likely comment anyway, so there's really no need.
God no, way too many people would be liking stale shade and it would only increase stan wars. Also, the posts that praise artists that are popular on ATRL would get the most likes. It would look like they won the discussion when the other person actually made good/better arguments. It would really take away the best qualities of the site.