Maybe because it is the climate we live in, here in northern Australia (i.e. tropical) but a good number of our swinging friends are naturists/nudists, as indeed we are.
The freedom of enjoying the outdoors sans clothing has certainly enhanced our swinging experience; we have met several couples and singles at our local (legal) free beach, sometimes engaging in activity right there at the beach or in the bush which backs our beach. Or we go home with our new friends.
The only problem is, like at so many nudist beaches, is the large number of men who seem to be voyeurs. They are not even nudists, but they are seen hiding behind trees clothed but with exposed genitals.
We have swung with guys we have met at the beach but only those who are nudists and whom we have approached. Only once have we accepted an offer from a single male who has approached us.