>>2875801As long as it's just dirt/soil, her feet can be dark brown from mud up to her ankles for all I care. An active, happy girl, who doesn't shy away from wading in mud is actually pretty precious and adorable. It only gets weird and kinda gross if she also wants to go toes bare in piss and feces. Or scary, if she also wants to take unnecessary risks with hazardous things like broken glass, or strong chemicals that could actually badly hurt her feet.
But in general, I like seeing feet that have been properly used in their natural, bare state and have the thick skin and strong muscles of the sole to show for it. You'll recognize a foot like this from the pretty satisfying shape they tend to have, having developed the proper musculature and splayed toes from just being able to move and work freely. Definitely props if gravel, or even snow is nothing to her bare feet.