It depends on place to place one beach I frequent, I wouldn’t bat an eye if I saw one. However in most saunas and social nudity settings not only would wearing a cock ring be stupid but also extremely selfish and disrespectful.
Even if there is “simmering sexuality” in these places (I’d say it’s no less simmering than any other bar or social gathering) by putting your parts on display with a ring you are making things very overt. We all love to fantasize about women staring at our cocks and all that but in reality 85% of women in these spaces don’t want to be bothered. If you wear a cock ring in a space like that all you do is make women uncomfortable and less likely to come back.
Women in the nudist community gossip often and if a place gets a reputation as one where creeps go to show off (even tho let’s be honest isn’t that why we are all in these places
) the reputation sticks and it can take a while for women to get comfortable going back. So for the sake of all of us pervs having a chance to enjoy some wonderful ladies bodies leave the ring at home unless it’s an explicitly sexual nude space!