I don't, but I get told to "smile BIGGER" all the time. I've been told that my smile makes me look nervous, and I've practised smiling a lot in the mirror... haha. When I smile for a camera, what felt like the smile I practised in the mirror does end up looking nervous and turned down in the corners. I just try to ignore people who tell me to smile bigger or happier, because I do smile and I feel happy when I smile, even if it's a different looking expression than other people call normal smiling. Whatever, dudes!
But for people that don't smile at all even when they feel happy, I get annoyed hearing people do that to others. People stupidly worry more if someone's mouth is curved a certain way than they worry about the person's actual feelings. Someone can feel terrible inside and if they smile everyone will assume they're fine. Telling someone to smile is selfish. If they think you're unhappy, a kinder thing to do would be to ask that person what they can do to make them feel better! Then, if the person is happy, they can tell them they're fine.
It might be annoying but it's much less selfish than just saying SMILE!!