Two very fair points, Matt.

I'd certainly have thought twice before doing my LKJ routine in public and, having just checked, I find you're right about Cash saying "they" rather than "dey" in Redemption Song as well.

It is true that "Dey rob I" seems to take it into the realm of caricature, while "They rob I" doesn't. Just that one extra little step that does the damage I suppose...