Mistress Tiffany was after dominating this guy and she knew it had to be a cruel thing for it to work. And that is why she went to wade in mud before she asked the guy to lick her feet. She knew that it would be a crazy and cruel ask but she did it anyway. And she loved the outcome as he had never had such a thing done to him.
Mistress Tiffany felt that her slave was not responsible and it pissed her off. She had to teach him how to behave and she felt that using her dirty feet was the best way to do it then. She used her big boots to trample his face and she also forced him to lick them while she smoked and she spat on his face. He got the message she sent him.
Mistress Tiffany wanted this guy to learn that she does not entertain any nonsense. So when he was done with the work she had given him, she paid him with humiliation. He was stripped naked and he was forced to lick her muddy boots. He had to do it until they were clean before he was allowed to go. He could do nothing about it and realized the mistake was his.