I apologize if it has been mentioned previously in this thread; but fyi, ALL horses except greys clip out to a different color at certain times of year depending on the length of coat, because the pigment in the hair shaft concentrates at the end of the hair shaft as it grows.
So black horses usually clip out to a mousy matte grey, bays clip out to a weird gun metal grey, chestnuts clip out to a weird pale orange, etc.
If you see a clipped horse that's retained vestiges of it's original color, it's because the owners clip frequently to minimize the color change, or that the timed the clip right as fresh coat was coming in.
So I'm not really sure the color of a recently clipped horse is a reliable indicator. New fresh coat growing in, before it can be sun bleached, might be a better indicator.
(The exception to this is foal coats - we used to clip patches of foal coat in order to determine actual base coat color for registrations.)
My favorite story about this is once I had a really cute large children's pony, mostly Welsh, for sale that was true black with some chrome. Gorgeous and flashy, looked like he was wearing a tuxedo. Had a 4" long Welsh pony coat.
Showed him to first time buyers, and when the came for a second look, I told them I was very glad they had come back, that I had clipped the pony and he no longer looked like a stuffed animal, you could now actaully see his confo.
I pulled him out of the stall, this gorgeous, slick, typey thing, but definitely matte dark grey, not black; and they looked at me like I was they worst crook on the planet and said "YOU MEAN THAT WASN'T HIS REAL COLOR?????"
In his case, yes, black WAS his real color.
But I will never forget the look on their faces because they thought I was playing some heinious trick on them.