Debra is a clean freak. She does not want her shoes to even have a speck of dirt. She had stepped in mud and she came home and made her slave lick the mud off her shoes. She wanted it done first or else she would beat him up in addition to him licking the shoes clean. The poor slave tried to accomplish everything as fast as he could to avoid the punishment.
This mistress made her slave lick her dirty soles before using the same shoes to torture and trample him
These mistresses wanted to show their slave what they were capable of. They made him sniff and smell their dirty socks and kicked him before making him lick their dirty soles
This mistress was feeling down. She got her slave and made him smell her sweaty and stinky socks. And it made her feel better