My do has always had his personal central heating - though perhaps less efficient in the last few years - and will wear shorts whenever possible, inc. just the other day. His legs are perfectly presentable so it's fine with me. (Wish I could say the same for mine! I won't be seen dead in shorts nowadays.)
I know what you mean, though - there was a man who used to come into the library where I worked, who wore them all year round, even with snow on the ground. He was (probably still is) an extreme eco-warrior, evidently didn't believe in shampoo, either. His hair didn't look dirty, but you could smell it - that horrible unwashed pong that's rare nowadays - from quite a few feet away. BTW he wasn't homeless or anything, in case anyone's wondering.