Are there any attire requirements for male travelers in Iran? There are many reports and much advice that women should dress conservatively and we have a related question about headwear for women. But what about male travelers? Are there any requirements for them?
To make the question practical, would a T-shirt and shorts be acceptable for male travelers? Would it be legal, tolerated from tourists, frowned upon, anything else...? Would the reaction to a Western male in T-shirts and shorts be different in Teheran than in the mountains or the countryside? And what if you would be doing sports activities like running: does that change acceptability?
I am not worried about sticking out or being the source of giggles but would like to avoid harassment or hostile reactions.