This "drive by down-voting" happens regularly here. I've had comments downvoted within seconds of posting--clearly the voters could not have had time to read the entire text. They see a few key words that trigger them, hit the arrow, and move on to the next job. Unfortunately, there's no way in JavaScript to tell whether someone's actually read the thing they're down-voting, so we get these knee-jerk keyword-based brigades.
To test this, sometimes I'll write something where the first sentence is provocative, but the rest is (I hope) a solid, nuanced argument. Usually it's at -1 or -2 within a minute, and then over the next few hours slowly crawls back up to +2 or +3 as people actually read it.
I cannot but confirm this behaviour.
Also I noticed that (my guess is that there is some form of subliminal self-defense reflex by some categories) there are a few themes (not political, not social) that seem to attract downvotes.