i was once taking out would-be sailors in my int 14 at a club open day and there was a press boat from a local paper taking pictures. as i sailed past the lady reporter told me to stop smiling, i replied 'why, i'm enjoying myself?'
she still managed to catch me in a 'off' moment and my scowling face duly adorned the paper the following week.
perhaps it's a question of 'scowl, you're on candid camera'