Found this thread while doing some research. I wonder if that judge was referring to body color paint on the underside.
I checked my untouched parts truck and, under some undercoating, there is some black paint or probably primer. I'm speculating the "correct" process was all cabs started as all black primer. Then the top side was sprayed with color and some overspray probably drifted in along the edges. I've read that the hoods were done the same way - underside black with some body color spray along the edges. My two factory-original trucks support that as well.
