chalst: My experience is that the account deletion threshold is set so (artificially) high that the only way to get a spammer account deleted is to mark them down as spammers unless it's dead clear they're not. Even then lots of fake accounts get through. Mostly the real spammers don't start spamming immediately; they appear to be accumulating fake accounts and holding them in reserve.

Anybody who gets their account deleted can just sign in again and behave less spammerishly next time, so there's no reason to use kid gloves.