I don't know about this. I know professional musicians and they say that they make little mistakes all the time, but part of being a professional is being able to pretend those mistakes didn't exist because the audience doesn't know what it's supposed to sound like.
Very true, however it's something musicians have to specifically train for, because to a trained ear they can become painfully obvious and it's tempting for the musician to (at least) cringe in a way that the audience will detect. Musicians in the audience, though, can often tell when you flub a note, regardless of how you play it off. That's really the bar we are looking to meet.