A Sheraton I once stayed in (I don't remember where, maybe Dubai) had a sign saying no outside food and beverage allowed. I find this outrageous, would have no compunction about violating their rule, and made it a point not to stay there again on principle.

Naturally, their rationale was some bogus statement about "health and safety."

The Wynn in Las Vegas used to have the same rule, not sure if they still do.