I couldn't agree more LS. I used to get it a lot, maybe I have that kind of face, but even if I wasn't feeling sad, just thoughtful or concentrating, someone would say that. It's hard to know what to do, do you act grumpy even if you weren't before or do you 'obey' and give a big fake smile because someone told you to?
Some of the buses I ride on have a sign in the windscreen saying 'SMILE'. This really annoys me because although I always say good morning to the driver, and often have a joke, I don't appreciate being told to. I'm a paying customer, I'm not mean or nasty, I'll decide whether I'll smile. Another thing is that the
driver is often the grumpy one!
Anyway, in closing: