So, i really have two questions, the first being in two parts: do you vote for posts (up or down), and why?
Yes. I do both. I vote up posts in which are creative, funny, and/or make a good/great point. And I've adopted the habit (from Dutchy) to thumb up the person's answer above my own in the word game threads.
I thumb down posts with which I have a strong disagreement with politically.
The second question is, do you think there are people who go through threads merrily voting posts down to amuse themselves?
I suppose there are those who hold such practice. There are also person's who hold personal grudges against certain members where they will actively thumb down said member's posts even when that person's posting has nothing to do (apolitical, uncontroversial posts) with the disagreement the two parties have with each other.
If I see this out of place thumbing down, then I will thumb that person's post up to rectify the situation.