Oh god I missed that first time through. I'm quietly gagging thinking about shirtless dudes rubbing up on the weight machines before other people get to them.
I assumed she meant like running on the treadmill or something. Maybe playing basketball? Still a little on the side of icky if you ask me (because of sweat and skin germs, not OMG nudity).
Only at a pool with a thick layer of sunscreen. The sun and his skin are not friends. He often goes shirtless when we're home, but he puts a shirt on if he has to go outside.
I've never seen DH do it in a "public" place. Once in a great while, if it is 90 degrees out and he is helping a neighbor with heavy manual labor, like digging a trench or something, DH might take his shirt off in a neighbor's backyard so he can hose himself down. That's about the only situation where he would be shirtless in front of others.
Sleeping and swimming only. Years ago in grad school he insisted on biking home from campus shirtless (summer in the south, so it was hot and humid). I was so embarrassed that I refused to ride with him. I think he got the message because he never did it again. At the time I felt like an asshole, but after reading this thread I feel redeemed!
DH walked to the public pool with me the other day with no shirt on. This is the only time I can think of that he has ever not worn a shirt other than at our own home/cottage/beach.