The Villan is right on. IF there is a contract that contract will almost always set the rules about CD sales - and if a venues says no CD sales (I can't imagine why any would say that) then there are no CD sales.

Actually I have always found venues to be accommodating with respect to CD sales. They realize it is an important part of a performer's income and normally want to be helpful in that regard.

BUT even if there were no rules established in the contract with respect to CD sales - the venue is the host. Their wishes should be respected by the visiting performer.

If any of these issues are not pleasing to both parties - they won't do business again. There is never a need to get into pissing contests over such things.