Sometimes I'll look through comment chains on slightly older threads and see posts where someone obviously up-phuked and replied, but never got a vote back. I like to give those people an up-phuk, not to be nice and make them feel like they made a good comment or anything, but to think the person they replied to gave them that up-phuk if they ever check their comment score. Note I do not vote on the parent comment so it ends up often being 1 on both parent and child comments then.
Does this make me a bad person?
I'll do that occasionally too... just one example of voting based on others' votes.
Edit: Perhaps the motivation is different from you, I'm not so concerned about where people might think the upvote came from.