The conduct issue aside ( electronics, not showering etc) The biggest reason a lot of guys wear shorts, or towels or otherwise is because of the proliferation of guys trying to hookup in the steam or sauna, so so many guys whether they are gay.straight, or bi who just want to chill are constantly bombarded with advances or walking in on others. It is like an epidemic here in NYC lol. I mean just go into the craigslist missed encounters..every other one is about a sauna/steam hook. interruption etc. Even dudes who are into dudes, but who just want to use these things for what they were intended for cant catch a break.
The hygiene stuff...well it is what it is. some people are just fng gross. lol
I can totally see how guys cruising for sex would ruin it for everyone, but honestly it hasn't been a problem where I live. I'm sure it happens here but it seems to be super discreet because I've not witnessed guys doing that in our local facilities. Not to say I've never been propositioned when away from home. .it did happen when I was in the US once.
The very forward behaviour towards naked guys in the sauna seems to be very much an American thing. The strong aversion to nudity in the US has led to it being far more sexualised I think. One time while on vacation in the US I was alone in the sauna, lying on my towel facing up as there was so much space, another guy walked in and sat down. I thought nothing of it and closed my eyes and went on relaxing. A minute or so later I open my eyes to pick up my water bottle for a drink and see that he is staring intently at me, has a full election and is masturbating! I said to him I don't think this was that kind of place (it was a spa facility in a hotel, not a gay bath house lol) and he could get us in trouble if he didn't put it away. He was good about doing that and giving me no further trouble so I didn't report him. BUT he did mention he thought I was signalling I was interested because I was showing my cock. Apparently in the US in some places nudity is so uncommon that those looking for sexual activity have made "opening the towel" some kind of signal, just like "tapping the foot" in public toilets (that one I learned about through the news, when a prominent politician apparently was caught in the public toilets at an airport tapping his feet and trying to get guys to gave fun with him lol).
So it is a vicious cycle that has to be broken somehow. Covering up has made nudity more sexual causing guys to harass those who are naked, which makes guys cover up to avoid the harassment, which reinforces the link of nudity to sex...and so on...
So my approach is to make people accept my nudity and do so respectfully by NOT changing my behaviour and reminding people to be respectful when they behave like that (and if they persist report them). I have never had to report someone for sexual harassment but I have done so when people kept bringing electronics in after being told it was not allowed, as well as being fully clothed and unshowered. In NYC it wouldn't surprise me that the sexual activity is a problem...all kinds of shit happens there that just gets ignored so that is probably why. Where I live such behaviour would definitely get reported (so do the dirty, mobile using clothed people, but since it isn't illegal they care less about it). But if the consequences are being banned and possibly arrested it would be a deterrent.