I workout in an inner city gym and most black "kids" workout shirtless. They don't even wipe the bench when they are done using it. One day I went up to one and asked him if he was from San Francisco? He looked at me like I was crazy. I said all the gay dudes do that. He said, "What"? I said "Workout without a shirt". He walked away looking even more confused then he started.
I would have looked at you strange too. And the fact that you know what Gay dudes do, would have either come with a beatdown...cause you in essence were calling him gay, or hitting on him. You could have just said, "Dude, can you wipe up behind yourself, you left sweat on the bench? And you might want to lift with a shirt on, because you'll leave sweat on things, otherwise."
Simple, no need to allude to anything.