It's definitely going to be enforced promise.
It is a big liability issue when glasses are smashed all over the ground, drinks are spilled causing the floors to be a little slicker and also getting your toes crushed when people are dancing/moshing.
Really it should come down to common sense, but seeing how people have a hard time reading the signs on the doors for which is in and which is out. I really don't think posting a sign will help either.
Only Kate Moss is allowed to wear flip flops at the Cat. lol
MindCage
Mindless Faith Deep6 Productions