This mistress wanted her slave humiliated because he was almost useless to her. So she used her socks to do so. They were dirty socks and she had him lick them and endure being trampled with them too. The mistress could tell he was having a bad time as he did what she ordered. But she had fun seeing him suffer so she let it go on as long as possible.
Mistress Hanna was in dire financial straits and she needed some money urgently. She knew this guy had it but she knew he would not lend it to her as she had tried before and he did not give it to her. So she forced him to give it to her by trampling him with her smelly feet and with her stinky socks. He was scared of her and he gave it to her.
Mistress Cleo wanted to make her friend see some sense because she was afraid that her friend had thrown sense out of the window. She was about to make a mistake he would regret and it was mistress Cleo's duty to stop that from happening. So she used her smelly feet as well as smelly socks to dominate and humiliate her friend to make her realize what she was about to do was not good.