This mistress needed to send a message that this guy would never forget and that is why she chose to teach the guy a lesson that no one had ever taught him. She chose to make the guy learn his lesson the hard way and he cried at what she did to him. He begged her to stop but she did not as he had to do it all. He had to lick her dirty feet and shoes clean.
This guy needed to be put in his place and that is what this mistress did. She had to ensure that the guy did what he had to do and that he knew his place. He seemed to have forgotten and she did not want him to forget. So she reminded him with her foot fetish. It was humiliating but there was nothing he could do about any of it.
Mistress DirtyQueenPenelopa needed to find a new way to punish this guy and she did it with her smelly and dirty feet. She did not care what this guy thought and she knew that the best way to do it was to turn him into a foot slave and have him lick her feet as well as do some humiliating things. That is exactly what she did to him. He cried.