If the guy advertises publicly somewhere, like viva local, anything goes, except what he is not giving in his ad. For example if he doesn’t have a face pic, then it would be out of order to post a face pic of that guy.
For grindr guys, I wouldn’t post anything that reveals his identity, but would be happy to describe the sex in detail, purely for entertainment, though, because I don’t expect anyone to find the same guy, grindr is not fixed, it shows people depending where you and they are, unlike an ad.
For sauna guys, I feel the real identity of the guys is out of order, so no face pics unless you have explicitly asked permission. But their sauna name is not their real name, so I have no issue posting that and the details of the sessions. After all they are selling a service which is legal, and we should be able to know who is good in the cabin, and who isn’t. We can only do that if we ID them by their sauna name. And the only people who will be able to find them from these posts are people going to the sauna, which to me is just like talking to another patron at the sauna itself.