Mistress BlackDiamoond took her slave to a secluded room and tortured him. She made him lick her feet and made him smell them. They were dirty and smelly and they were in perfect condition to be smelled and licked by the slave. She was punishing him for not following the simple instructions she had left when she went to work that morning. That would teach him an important lesson he would never forget.
Dirty feet are Kitty Devine's fetish. She likes to have them licked and smelled. That is what actually turns her on. If someone does not do a good job of it, she uses them to trample and punish him or her. If the person does a good job, then she can even have a footgasm. That is why she loves using her feet on slaves and why they are special to her.