Things that need to be addressed

> Porno providers are often willing to acknowledge that they are serving porno
> (after all, it is difficult to hide once the site is up).  

Sure.  But Spammers don't.  And there are also many arbitrary errors in the
filtering services (again, see http://peacefire.org/), which are amplified
1000x if you cluster 1000 sites on each IP address.

Kevin