One way that I have used up/down votes, particularly on comments, is to surface the most valuable information. For example, if a post has valuable content, that is patently useful but it isn't the top comment I will down-vote the top comment(s) and upvote the valuable one.

For example, if someone posts a question and the top 3 comments are low-effort jokes, and the fourth comment is the answer, I would down-vote the top three and upvote the 4th. In an effort to surface the best information.

Now, I try not to do this unless I'm certain of post 4s quality. And usually not unless there are enough votes that a joke-commenters would feel personally picked on, or like their joke wasn't good.

Other examples of good comments (by my reckoning) are: transcriptions, useful links or context, proof, other examples of the same thing. Or somewhat verifiable reasons why the post is unhelpful or misleading.

The crowd isn't always right. But it can provide useful context and I try to be a part of that.