Often if you go back later, you'll see that the downvote has been "corrected" by another reader. I'll sometimes upvote a reasonable comment only because it has

Often if you go back later, you'll see that the downvote has been "corrected" by another reader. I'll sometimes upvote a reasonable comment only because it has negative karma. And I've... uh... in the name of science, made some relatively useless disagreeable comments that had downvotes, then upvotes, then downvotes,... before reaching equilibrium at +1, so other people do too.