OMG, my cat has skin after all! Every other time I've tried to part her fur look, all I've found under her fur was more fur (leading me to believe that she had no skin, but just transitioned directly at some point from fur to stomach), but this time I got to see skin with hairs growing out of it instead of Yet More Layers of undercoat.
I think she has dandruff. There are little white flakes sprinkled through the hairs that come off on the grooming brush.