Some guys go over the line - whether they are gay or straight. Generally, you just ignore them - what's it hurting? They're sad and lonely, and clueless. IF they touch you without consent, however, pop them in the nuts with your knee (I have), or if they are quite a bit bigger than you, report them immediately. Not cool, ever.
I had a guy climb into a shower stall with me, and start sucking my cock while I was shampooing my hair (so much for private stalls, huh?). I kneed him in the neck. He was surprised, as he was coughing, why I wasn't happy with his attention. I told him to get the fuck out, or I would call the police. It certainly surprised the hell out of me. I was pissed off. I never saw him around there again.
That said, mutual JO in the sauna, shower or steam room is the bomb! Only if everybody is "up" for it, however. My LA Fitness waxes and wanes as far as clientele during the day and evening. There are times it's really cruisey, and times it's not. But if everybody is up for it? It's one of life's greatest pleasures, and something that is uniquely male - a celebration of being male - whether you identify as gay or straight. Our culture doesn't have fertility celebrations or anything...this comes close.