What does "swinger" mean in relation to a nude beach?
Well, speaking of Valalta, there's a part of the beach, very crowded, with couples and single guys, and most of them have or share sex, in front of the others.
So, you can find just a couple who plays, or fuck, or a single woman jerking off o sucking more guys, or 2 couples changing partners....well, every possible combination

Cap d'agde has always been in this way, people knows and nobody complains about it, rather this fun is a big inducement to the tourism there; but not the only one. As I wrote in another post, there are many families, every age, and a pure naturism.
PM me if u need more specific informations.