I can't really say.
Most of my (future) flesh tones have been based on some of Doc Rob's mixtures, along with a few of my own. If possible, I try to use different fleshtones, browns (such as Apple Barrel's Chocolate [Bar], Brown Oxide, and Toffee), and maybe white -- if not pale enough -- to mix skintones. My goal -- if planning a custom of an existing Joe/Cobra figure -- is to try to match that figure's original Hasbro-given skintone (so far, I've successfully matched

, and have come close to

). If doing an original character, I can choose to match an existing Hasbro-made skintone, or mix the colors I have to see if I come up with one that works by myself. I'm still working on a choice Native American skintone, but I like the one I've developed so far.
-- Cybertronian.

P.S.: If you want an "ashy" (moisture-deprived) African-American skintone, try to match 1991's Heavy Duty v1. Being from Chicago, I guess they were trying to go for a "doesn't sunbathe often" look. Down South, we of color tend to have both "winter" and "summer" skintones. (or at the very least, a "you can see which arm faces the outside window when driving" skintone.)