What does motivate you to down-vote a comment?
SwellJoe: I have to be pretty annoyed to downvote.  I almost never vote up or down, actually, and downvotes are extremely rare.A personal pet peeve is when someone willfully misses the point of an article or comment in order to go off on some pretty much unrelated tangent.  It happens on reddit more than around these parts (I suppose because politics are free game over there and not welcome here, and politics bring out the worst in people), but it happens around here occasionally, particularly on religious topics (Apple, text editors, pg essays, programming languages, etc.).Plain old stupidity will do it, too.  Willful ignorance, spam, self-righteousness due to ignorance of limitations (e.g. a "business/idea guy" looking for an engineer and offering a pittance for the work being shocked and angry that no one wants to work with him), that sort of thing.I'm more forgiving of stupid posts if the poster recognizes their limitations and can laugh about it.  Humor goes a long way towards nullifying any annoyance I might be feeling about flaws in a post.