It absolutely existed and I remember it well. It apparently still does in some form even if it is only virtual.
See http://www.darkside-goddess.org/

It eventually had a quirky name “Essemian”…a play on “S&M” I assume attached to it. It appeared fairly regularly in the fetish print media of the day in one form or another. That era, pre-internet, saw a lot more “not just a party per se but group types of things” going on. The Till Eulenspiegal Society in NY was an example and there were others.
As an east coaster I was more personally familiar with the Eulenspiegal society and those in that region. I only met one person who claimed to have visited it in California and he said it was a bit “weird”. I asked what he meant and he said “a bit weird like you would expect in San Francisco and a bit normal weird”.
I feel the AIDs epidemic, post 60/70s fatigue, and eventually the internet killed many, maybe even all, of these off.