If I do blush then it doesn't show, because I'm black lol. I imagine something like that would be really embarrassing since you can't hide it. I do feel myself getting all hot so I bet it would show if I had lighter skin.
Sometimes, I blush if a lot of attention is drawn to me. I also have a problem with facial sweating, which can be even more embarrassing. I have no great solution. I've noticed that the more you pay attention to a problem like sweating or blushing the worse it gets. If you can get your mind off of it, it will sometimes go away.