To be fair to Biden he did say "mainstream", which is Biden (and MSM) speak for "far left liberal", so I think he's off the hook with Watts. I'm sure he (and the MSM) would try to classify Watts as an "extreme right winger".
Fine, then let him elaborate on which mainstream Af Amers are not clean, to his way of thinking. And not bright or articulate.
I don't care how you define mainstream, somebody---make that a lot of somebodies are getting trashed here, all of them African-Americans. As such!