It is a matter of fact that Mia don't like sperm on her soles. She doesn't like to accomplish her slave's pleasure ALL THE WAY. At the same time she doesn't want to give a reward, without some thrilling and sadism. She makes her slave aroused with her left foot sole, trampling his dick and massaging it up and down. When the man is very close to cum, she changes foot: the right has got a dirty house slipper. The man is so exited that he releases tons of sperm anyway.