They "usually" attempt being so discreet. Many times clubs such as these have names (generic sounding to public) and I can see asking for a discounted rate because you're with the... let's say, "Full Moon Club". No one would have to know what the club "rules" are or how they're enforced!

Actually, DH and I know a bit more about this than we EVER wanted to know. One of the other engineers DH works with belongs to one of the swinging clubs here in Central FL and he's told us ALLLLL about this mess!