the ugly history of minstrel shows, but wearing reggae attire with dreadlocks? If someone gets offended... f' em. That's their problem. But unfortunately that's not the way it works.

Where I draw the line is
a) blackface, as I said because of the ugly history. It's off limits even if it is not done in a way intended to mock or demean
b) anything that enhances/reinforces negative stereotypes (your "ghetto" example)

I personally wouldn't go there as you say with the Bob Marley costume, just not worth it. But it shows how stupid and uptight we've become.