Is Applying Makeup in Public a Do or a Don't?

This morning I boarded the bus, only to notice a fellow rider putting on her makeup. I'm not talking about a little touchup, either—it was the whole shebang. She plucked product after product from her bag: foundation, concealer, powder, eye shadow, lip liner, eyeliner, mascara and so on. By the time she pulled out the eyelash curler, half of the bus riders were trying not to stare. DearSugar and I agree that it's a tacky transit don't. What do you think?