Mistress Natasha had a new slave and she did not want him to think that she was soft. So she projected strength by dominating him using her sneakers. She did not want to make it painful as he had not done anything wrong to justify being punished but she wanted it to humiliating enough to send him a message that he was not to mess with her in any way.
Mistress Isabella was angered by her neighbor trying to anger her every chance he got. It felt like he got a kick out of making her angry and she was not going to let anyone bully her. So the mistress shocked him by using her sneakers to trample him. He was even forced to lick them despite them being dirty. And that is when he stopped messing with mistress Isabella.
Mistress Valeria and her friend mistress Anna wanted to try something new. They were bullied and they wanted to test whether this girl would be scared of them and do what they wanted without them doing anything to her. They just wanted to scare her with words but not touch her. They did so and after describing what they would do, she agreed to lick their sneakers until they were clean.