Thanks Ruth for letting me know that asking for black coffee is fine in New York State. Looks like it was an urban myth after all, though it doesn't detract from my point. Meself, it's easy to sneer and perhaps I deserve it for being gullable, but honestly, in these days of frantic paranoid PC who can say I was entirely foolish to be mislead. The fact that a radical black comedian found extreme (though fictional) PC views derisory 40 years ago might be of interest.
Incidentally, just got my latest copy of Folklife West Journal which has a short article on the Brimfield (Herefordshire) Border Morris side of 1909. It mentions that they blacked up, but some had white paint patches. The illustration shows one member with white circles around his eyes, and another with a white area around eyes and nose.