This email was sent out to gamemasters regarding ingame casinos:
It may a bit less profitable (more chance of being ripped off), but if you collect your casino money afterward, there is 0 chance of being banned.A quick FYI, as an ex-member of the GM Team, and current member of the community team for Blizzard Europe SAS, Casinos that take an upfront entry fee (items or gold) for a chance of winning a prize based on any means (Rolls, quiz etc) is against the terms of use and will result in action being taken on the casino owner.
The collection of the entry fee is the violation. A Casino that offers prizes without an upfront fee (like a competition rather than a casino) is perfectly legit, hence the answer you got from the Game Masters may have been wishy washy!