My site has lately been targeted by human spam... meaning people taking the time to carefully complete my registration process, confirming via email, and then letting the member account sit dormant for a week or two... before invariably filling the profile space with advertisements and links for handbags and luxury watches and the usual crap.
The most recent sleeper account popped up this morning, where an odd but not quite nonsensical username caught my eye. Checking the server logs, this person registered from Jiangsu, China and the browser referrals were other sites' login pages, so it was clear this person was working down a list.
Anyways, the anti-spam account literature I've read focuses on strengthening the first line of defense - your registration system.
But what can I do to clean-up those few who can run the gauntlet?