For this club especially, voyeurism is common.  That's not always the case and many clubs will have places where couples can go for privacy.  But a general rule is that couples should expect to be seen naked by strangers if you're off in the play rooms having sex.  It doesn't mean that couples should expect to have strangers jumping on the bed with them unannounced or talking to them (or commenting) while getting active.  That sort of behavior will get your ass tossed out past the curb and into traffic.  But being observed while getting your tingles tasted... yeah it's going to happen.  As long as it's done respectfully and not creepy.  Buttergollem in my story was doing it right by sitting quietly and just watching.  If the fit couple wanted to her to leave, they could have told her and she'd be obligated to move on.    I wouldn't be surprised if they just forgot about her sitting there.  Being watched can be uncomfortable, but once your body has to decide between arousal and awkward, arousal wins out.  If it needs help, that's what alcohol is for.    On a side note, lots of the mirrors in the place were two way mirrors.  So you could be in a private room, with a two way mirror facing out on a couple having sex who couldn't see you.  It's a place that takes a bit of adjustment, but we're looking forward to a return visit.