Not saying I'm going to do it but you can't compare this to other ethical medical issues.
The C doesn't reflect me. If you get a C in a class and you re-take it and get an A, then I don't really know what the C means. You either understand the material or you don't. Having said that, if you repeat a course, the good grade should reflect your understanding of it. Even if you take it 20 times and then get an A, that means you got it. So if AMCAS is going to decide whether or not I become a doctor based on something like that, the thought will naturally cross your mind.
My idea of not revealing a bad grade is no different than a woman saying she is younger than she really is or men dying their hair to remove the gray.
It's not like I'm going to end up a doctor who performs third trimester abortions in my basement.