[philipkglass]

Most of the comments I downvote the official comment guidelines in the section "In Comments" here: https://news.ycombinator.com/newsguidelines.html

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.