The toddler strategy
Most people don't get too upset at anything a two-year-old kid says to them.
That's because we don't believe that toddlers have a particularly good grasp on the nuances of the world, nor do they possess much in the way of empathy. Mostly, though, it turns out that getting mad at a toddler doesn't do any good, because he's not going to change as a result (not for a few years, anyway).
Couldn't the same be said for your uninformed critics? For the people who bring you down without knowing any better, for those that sabotage your best work, or undermine your confidence for selfish reasons?
It's hardly productive to ruin your day and your work trying to teach these folks a lesson.
Better, I think, to treat them like a toddler. Buy them a lollipop, smile and walk away.