If you ever get a chance to go to Berlin, Laboratory on Thurs night is naked night, even the bartenders are naked. I was number 502, the place is huge and there's a doorman that rejects people, kind of like studio 54 if he feels you don't fit in....too fat or too old I guess, he let me in every time, maybe because of my tattoos since he's totally tatted?
Everyone inside looked decent, there were older guys, but in shape and well groomed....
Doors only open for 2 hrs 9-11pm and after that no one can come in and once you leave, you can't come back in. So no one is waiting for "something better" to come in, like we gays so frequently wait or go looking for. It's the most memorable place I've been to for a naked night, sauna mania is fun, but too many shy guys for me, even on naked night.