They'll ban you when you're talking politics, They'll ban you when you're trying to get your licks, They'll ban you when you try to make a buck, They'll ban you and say it's just your luck, But don't feel so all alone, Everybody will get banned.

(With apologies to Bob Dylan...)

Serious point, though: They can decide to ban (almost?) anyone at any point. They will state a justification, but it looks a lot like banning anyone whenever they decide to.