Happen often?

[Desotomiss]

We have been on again off again adult play for twenty years or so. Occasionally, we are just out listening to a band or at a concert and we just get approached by another couple. A couple times we played with the random couples and was ok, I mean if she's up for it, he's always up for it lol, especially when she finds a girl she likes, man, watching her do another woman makes him feel like he has a lot to learn still.
We also did the cliche pizza thing once while visiting Chicago. We had this favorite pizza place, after happy hour one night, back at the hotel and ordered a pizza. When the dude showed he stepped out into the hallway with delivery dude and asked if he would be comfortable taking some pics for and with us. One thing leads to another and he got some great pics of nice cum covered tits ..a favorite. (Second only to a LOT of cum on the tits lol)
We are just wondering if this is pretty normal for other open minded couples or have we just hit a few lucky streaks (no pun intended). Don't get us wrong, we don't just walk around having sex lol, just wondering if others who are open to it, have had similar unplanned romps.