I've seen dappling.... and some that seem to be dark under the hair on their body. Especially in the blonder shades.... I just googled on "palomino" and found this guy.... he's got the same thing going on in his loin... and more distinct dappling.
I'll have to check tomorrow for sure, but I think the hair is gold like the rest of him, but he has that shoulder and spots that the skin is darker. I've always thought that was odd, and kind of glad when it didn't show so much. I'm not sure I like it.
Becky