These mistresses are adventurous but they had never tried naughty things like foot fetish. So they got their feet dirty and used them to humiliate this girl. She owed them and they knew they could humiliate him and torture him without having to worry about much. They forced him to lick their soles and the poor girl finished licking their dirty feet and had to lick their toilet. It was a great experience for the mistresses but not for the slave girl.
Princess Kitty did not want her slave to mess with her. The slave was new and she wanted to teach him how to do things in her house. After she had shown him, she humiliated him cruelly. She did that to prove to him that she is not an easy person to deal with and that if he messed with her, there would be hell to pay. He feared her and never messed up.