'Don't do the pastie smile well, and my usual default setting is grim looking (I'm not exactly a lady-killer), but I do try to smile once in a while, especially when doing a solo thing. I admire those who can play convincingly and sincerely smiling all the while, but not me. Other indicators of "smile" may be present, like the eyes, and general body language.

Sincerity matters more. A shit-eating grin while singing a slow air just doesn't fit.

Don't worry, be happy.

Peace, Mooh.