[zmanda_it]

The acccounts in question are not banned at this time, but I found a way to determine which accounts are actually hosting spam:

SELECT username,t1.userid FROM vb3_user t1 JOIN vb3_usertextfield t2 ON (t1.userid = t2.userid) WHERE t2.signature like '%http%' or signature like '%href%' or signature like '%src%' or signature like '%url%' or signature like '%buy%' or signature like '%img%';

In my case, that brought the total number down to 37, which I can delete by hand. Hopefully this helps someone else.