I upvote stuff I agree with. ;)

But seriously, I do exactly the same thing. And like in other places, I always downvote rudeness and gross incorrectness, but leave slightly incorrect stuff alone. This last type of node often produces the most interesting discussions. Anyway, I'm not really that good at Perl, so I don't always know whether it's correct or not.

I upvote replies to me whether or not I agree with them, as long as they show some sign of thought.

I also upvote "thanks, that worked" replies (to anyone, not just to me).