"sort of stagey parody that's a pathetic and insulting travesty, as with, say, blackface minstrelsy"

I see what Bob is saying, but let me mention that in the 1960s, when I first got to see the BBC TV "B&W Minstrel Show" repeated on Aussie TV, there was none of that I detected. In fact I regret the passing of the show - 'done in by malicious PCers' - :-) - because it was more like an endless Broadway Musical (or those 1930s Movie Musicals) - costumes, lights, and brilliant performers - dancers, singers, musicians, and comedians, presenting older English and American 'Music Hall', more or less. And because of the 'makeup', no one knew or cared what the ethnic grouping of the performers was - they either 'performed' or didn't cut it!

I never detected any of the sort of negativity that Bob hints MAY occur. And MANY white very talented singers made a good living 'playing blackface' for many years.