Some examples from a club night i had (all on the same night)
1) sitting in the jacuzzi, couple sit next to me, woman on the otherside of the man. we start talking and seem to be hitting it off. after a while she starts playing with him and climbs on board, as i am watching, he turns to me and says, do you mind not watching.
2) sitting in the lounge, a couple walks in and starts chatting, she is more friendly than he. eventually she turns to him and says, can we take him (thats me) to a room, he says yes, off we go fun had by all!
3) sitting in the same lounge and another couple come in complaining that some bloke in the jacuzzi asked the husband if he could join in..... they said that was wrong you should always ask the woman about 20 minutes later another couple come in and basically have the same conversation in reverse
4) A woman on the bed in the round room is lying there playing with herself with a group of men watching, she has her eyes closed and none of the men make a move, after about 10 minutes she stops and leaves, she is heard to be complaining to her husband that the men were pratts in there because they didn't even join in.
Now don't get me wrong, i understand that everyone has their own rules, but perhaps some sort of signs would be better. I don't mean a signal, i mean an actual sign hanging around the neck of either member of the couple or both
example
1) you must ask my wife if you can join in, but only after she has spent 10 minutes sucking me off
2) you must ask my husbands permission to join in, but only after he is mounting me from behind
3) I (mrs) only kiss women, but don't go down on them
4) Neither of us is bisexual and will be very offended if you even suggest it!
you get my drift
you could even have them made with the logo of the club on them and pick them up at the door on the way in.....