I do occaisonally carry off body in some sort of bag, but it's generally when carrying an extra gun in the car on long trips.
I'm sure it's hotter in the summers here in NC than it is in MA and I often carry one and sometimes two guns on my person in shorts and a T-shirt.
It takes a combination of the right gun, the right belt, the right holster, and the right clothes, but it's very do-able.
I prefer revolvers for the most part and it's not hard to carry an SP101 on my belt and an LCR in a shorts pocket completely unnoticed by the populace at large.