i never think about it. I only rate when the QA comments on me to do so, or if they update the question and ask for it. otherwise I just don't think about it or remember to do so. 5 star for this one since I'm reminded of it :D
I either rate questions good that I like, or I'll rate it 5 stars if I think it's a legitimate question but people have given it a low rating. But I don't really pay attention to ratings on questions anyway, so sometimes I won't even see what it's rated.