While madame Marissa made her slave lick her boots, she felt that it was not enough despite it being humiliating to him. She felt that she needed to do more to dominate as well as humiliate him and that is why she chose to turn him into a human ashtray. That was painful as it was humiliating and cumulatively, she felt that he had learned his lesson and she let him go.
Madame Marissa had a lazy farmhand and she knew that the best way to deal with him was to use her hiking boots to trample him. That is exactly what she did to him and she made sure that there was a lot of pain on his part. The lazy farmhand learned never to be lazy again as he did not want to feel that kind of pain ever again.
Madame Marissa was out to boot torture this guy and she knew that she had to do it like a pro because she had to make sure that he learned his lesson from that one lesson. There was no going back and he had to do all that she said from then on. That is why she brought out her big guns and used the hiking boots to do it.
Madame Marissa wanted her hiking boots licked before she used them to trample the shit out of this slave. She had had enough of him and his behaviors. She had asked him to change many times before but he did not and she had no option but to punish him and so the mistress cruelly ensured that he felt the pain and that he cried and begged her for mercy.