One of my pet-peeves is when someone that I don't know asks me "how are you?" Why? Because they don't really want to know. In the U.S we use this question as social lubricant, we don't EVER expect a genuine answer. Smiles are the same thing. Don't get me wrong, if someone smiles at me i will reply in kind, but I'm not going to go around donning some phony smile. That said, I'm not going around weeping either. I think it's alright to go through life facially contented.

I had a conversation with mk a while back about "before's and afters":

It's impossible to know what someone is or has recently gone through. To expect that someone who has just lost their sister to cancer or has recently been fired from their job to smile because, "hey there are kids that are starving," is simplistic. We can never know what it is another person is experiencing. Empathy is an awesome human traits that is all too rare.

So, yes... "smile" but don't be the dick that judges others for not smiling. We never know if someone is in the middle of an "after" or perhaps they're in the middle of their third "after."

Smile, with empathy.