Thanks for commenting! It's true. A little incentive to comment makes for a whole lot of lousy comments, of which I get plenty. Usually I just ignore them, but sometimes the more amusing ones get used in creations. ;)
Here's a song I wrote a couple weeks ago about just that, called "Shitty Comments."
Just keep giving those people a good example. Some of them will eventually figure it out, but some will keep doing what they're doing forever.