i've only ever blocked a couple of people who sent me long insane diatribes about what a horrible person i am (ba<x>sed, i think, on my religious beliefs differing from theirs.) others are pretty block-happy. hard to generalize ;)
The second they spam or talk about their junk
Hey hey. Where you been
I only block the worst question queue hoggers, but since the ep changes that doesn't remove their questions from my view like it did before. I don't see any point in blocking people I disagree with.