"The same thing goes for dancing or exercising or partaking in any type of physical activity that we’re not sure if we look good doing. For all the self-consciousness we experience in these moments, the truth is that the people around us aren’t watching. Okay, maybe they are for a second or two, but everyone is more worried about themselves than what another person is doing"

This is very true, but it is universally true. It is not unique or specific to appearance. People are also afraid to appear dumb when they talk in public, whereas folks sitting in the audience might simply not pay so much attention to the speaker because engrossing thoughts/problems/worries are running through their minds at that time. Or, and even more so, if folks in the audience are up to speak next, they most likely are anxious and worried about how they will be perceived. People in general grossly overestimate about the extent to which others pay attention to their existence... both negative attention and positive attention.