While it hasn't happened to me, I have read posts from some who have been attacked. Basically if you have a low following number and someone tags you as a spammer Twitter will suspend your account. They don't contact you, just suspend you. Its up to you to plead your case to the Twitter gulag. The idea is that by teaming up with other patriots you get your follow number up (the magic number seems to be 2000 so I've been told) if someone tags you as a spammer Twitter will see you have a valid account and not suspend you.