Mistress Mara was out to dominate and to humiliate this guy and she did so using her socks. She made sure that her socks were smelly before she used them to degrade this loser. The mistress laughed at the guy as he licked and smelled them and he made faces as he did it. She did not care what he was going through. He had to do things her way.
Mistress Emma made her boyfriend lick her socks and her feet while she played video games. He had pissed her by doing things behind her back and she was not ready to even talk to him so when he tried to explain himself, she humiliated him by forcing him to lick her socks and her feet which she made stinky intentionally in order to humiliate him and teach him a lesson.
Madame Marissa felt that this slave took her for granted. He did not act like a slave and he acted more like the owner of the house. She could not stomach that so she punished him and she did it using her bare feet. She asked him to lick her socks and she even made him chew them. He was humiliated but at the end of the day he learned his lesson.