PaDoc, I agree with you. My wife has, very occasionally, gotten into the mood at house parties where we were comfortable and let it be known that anyone who had a desire was welcome. Her maximum in one night was about seven or eight, I think. But because it was a social event where most people knew each other, there weren't any problems at all.
She never had any desire to open herself up in the common room at our Swing Club. She felt it wasn't 'controllable' - her word. The few times she was into more than an MFM in that situation, we'd get a few guys we trusted into a private room.