I wonder whether in 100 years time the present fashion for white youths to imitate the dress and mannerisms of black rap culture will appear as racist then as minstrelsy does now. Apart from the blackface (which was only part of the minstrels image - would it have appeared any less racist if they hadn't blacked up but kept the other trappings?) I find it hard to see a difference - in both cases white people recognising and celebrating black culture.

It's important to remember that minstrelsy wasn't about ridiculing black people. It was a way of bringing the vibrancy and rhythms of black music to a white audience, and in a way which fitted the social mores of the time and meant that the white audience didn't have to face contact with actual black people. Yes, it was patronising, but that is how black people were viewed then. I'm not trying to defend it, but to put it in its context. It was the first step which led to the dominance of music of black origin in modern popular culture. It seems odd and offensive to us now, but that is to view it with modern sensitivities.

In modern times, blackface is all about context - there are plenty of situations where someone with their face blacked up would not automatically be thought of as racist, for example:

a miner
a chimney sweep
a soldier in camouflage
a poacher or burglar trying to make themselves inconspicuous at night

Why then when you see a blacked-up morris dancer should the automatic conclusion be that its racist?