Sorry, not much we can do about it. It's a Whack-a-mole contest. Sometimes we get the mole, sometimes the mole gets us.
There may be some additional, additional things we can do to keep the spammers out, so we'll see.
As of this moment, all spammers are officially on notice and have been placed on double-secret probation.
If that notice doesn't do it, we'll work on something else. :)