I had the opposite reaction to some people here - I thought Ming was really funny, but that Thomas Middleditch's Call for China was unlistenably offensive. It's sometimes not about whether the person doing it is racist, just that some things just rub you the wrong way. I enjoy Thomas Middleditch as a guest, I just can't stand that one part of his act, so I avoid it when I know it's there.
I don't think the argument about how everyone else acknowledging how racist something is, makes it ok, stands. If everyone knows, then why not stop it? Also, 'Asian' covers such a large amount of cultures, it's pretty much meaningless.