Why Americans don't allow men to be in briefs at the beach/swiming pools?

The nudist beaches here in NJ, the men are disgusting. It is either old, flabby men or gay men. However, if they did have one where everyday people went, I wouldn't care, I would join in only because I HATE tan lines. But I am one to shun the sun. I absolutely LOVE my smooth, pale mikly skin.