I may be wrong - just attempting to be logical....
It seems that the skin pigment is pink, and in the muzzle as my boxer matures, the muzzle grows and the white hair toward the opening of the mouth gets more sparse, thus showing more pink. He is white socked and his foot pads are pink as well. I personally like the look. His muzzle is black, white, and pink. Looks like Neapolitan ice cream :D