““Why are Robbie’s feet, slipped out of immaculate white gogo boots and slung over a movie seat in front of her, so filthy? That is between Quentin Tarantino and his god.”
I suspect it is just a California/Southwest thing. So many women wear flip-flops outside and go barefoot indoors that their feet are filthy - dark black filthy. It is probably more a depiction of reality than art with a message.
He has an admitted foot fetish which is showcased in all his films.