I’ve never seen any no speaking rules in Germany but “no flirting” is very much an implied rule and the way anon describes her has having a “good body, tits and butt” he probably might have been creepy before even saying anything.

I’m not a big sauna guy and thus mostly was there with my girlfriend. And in the setting where you’re there with a partner, causal small talk with strangers was quite normal. I think it heavily depends on being able to read the room.