Hey everyone, thanks for the replies!!
I know he won't truly dapple out, but I was talking those nice, healthy (and very faint) dapple horses get when they are in wonderful nutritional health. I am aware about grey horses and their dapple stages.
He has dark charcoal (black) skin and has some flea bites. The only true white marking I've found on him is a tiiiiny star (makes him unique, no one ekes ever notices it).
Well, I will at least get him to be a fat and very shiny horse (eventually)!
You can never take a Thoroughbred away from a horse crazy girl.