When I see heated back-and-forth discussion chains I'll often find myself downvoting several comments and upvoting none of them, because sarcastic quippy retorts to bad comments are also bad comments.
I'll also downvote comments for factual inaccuracy, particularly if I don't have the time to patiently correct them. This only partially mitigates the damage and doesn't really help the original author to learn. When someone writes a comment with just a single big mistake, and they don't seem to have a history of willfully repeating it, that's when I am most likely to write a lengthy reply with explanation and citations.
I once made a post that criticized the Anglocentric perspective of an article. — it was initially upvoted, but then became downvoted when UTC+2 went to sleep, and then upvoted again when UTC+2 woke up. — one can take a particular guess as to why.
Despite whether I agree with it, I upvote anything that I learn something new from.
Factual incorrectness is often downvoted, but usually only if there is a reply that points it out.
I lurk and post once in a while. What I’ve noticed is that rarely is something downvoted for being factually incorrect (relatively speaking). You just have to offer a perspective that doesn’t conform with the hive mind and the downvoting essentially amounts to censorship of opinions.