I don't see the problem with them considering you're not gambling with real money. However I would assume that they would either warn you to stop, or give you a tempban. That's assuming someone reports you.
I've never heard of anyone doing this in WoW, nor seen it. But I used to run one in EQ and knew other people that did, and to my knowledge the cracked down on casinos in that. --- Tachidin - 80 Blood Elf Paladin - Area 52