Tim
You say very few get thought - my I suggest you look at the registered user list since the 5 Jan 2013 we have had 49 new registrations out of the current 198 (25% new in just 1 month), of those 49 I would say only 5 or 6 are valid certainly only 4 have every posted.
Just look at some of the user names
"buy nolvadex"
"timberlandbootsuia"
"ixbkdwumguqm"
"longchampoutletlzv"
"GoledCasinoMr"
I think we have a problem
Why not moderate at the source rather than leaving the door open and then having to quickly shut it and clean up once they are in, I can't see the problem, so a user may just gave to wait 24-48hr to get access.
I hope others will support me on this, as your profile data is open to these hackers once they have registered