Got to agree with ZR1. I love getting pics of my wife. Many are posted here. But most of those are Pre-event or afterwards or posed pics where I brought a camera, knowing that there would be photo ops (i.e. Fantasy Fest). Most of our hottest adventures occurred spontaneously when I did not have a camera handy or I did not want to break the mood by routing around for my cell phone in a pile of clothes. When you're about to watch your wife in action with several guys (and hopefully getting some action from their wives), trust me, the last thing your my mind is "where did I leave me cellphone?"
Also you don't know how others will respond to a camera, and I can't speak for anyone else but as for me these situations do not occur every day. I'm pretty grateful when these opportunities come up, I don't to do anything to screw them up when they do things are going right.