Mistress Mae has been working hard helping a local orchard pick their cherries and apricots today. I wore sandals today so my feet are extra dirty for you to clean.
Saving all that disgusting filth, just for you... so you can taste it as you lick my dirty feet and fingers clean. I even have dirt in the creases of my neck. I order you to lick me clean, focusing on my extra dirty feet.
I've never seen such grime on my feet. So to prove yourself to me as my loyal and obedient slave, you proudly clean your Mistress' sweetly foul smelling feet, with a smile on your face all the while ;)