I dunno. There's a lot of stuff I would put on EM that they have decided not to allow, but I think Rob Zombie and Rammstein very clearly fall into the 'not metal' camp. I like both, but neither of them sound anything like metal to me, or to anyone I know that listens to metal in significant quantities.

It's not like industrial is an instant deny, either - Fear Factory, Blut Aus Nord, Strapping Young Lad, etc etc etc are included.

As for King Gizz, their rules are quite clear that one predominantly metal album is enough for inclusion.