If I like it, up vote.

If I am ambivalent but like that they are contributing in a constructive or humorous way that is a net positive, up vote even if I don’t care for it or agree with it.

If it has misinformation, racism/sexism/etc., is over the top hostile without justification, or is otherwise a net negative to discussion then down vote.

If I’m not sure if it is being sarcastic I tend to not vote. Poe’s Law is like Brannigan’s law, hard and fast.