I imagine Kirino's feet, after a long day of running track, must be absolutely disgusting from marinating in sweat, grease and bacteria. When she removes her shoes at the end of the day, she probably gets flustered at just how smelly and toxic her bare feet are; her own body betraying all standards of decency by producing an unbelievably lewd and slimy, biohazardous zone of filth within her own footwear. Shoes designed to look pretty and appealing, now soiled and turned into unusable, smelly, ruined trash by her own festering feet. It's almost amazing how an odor so potent and foul can come from a girl so cute. What a contrast!
The contrast would be captivating. On one side, you've got her beautiful, pale, shapely, happy feet. They're works of art, and can arouse anyone with their perfection. On the other hand, you've got endless of amounts of a stink so foul it can make plants wilt and birds fall from the sky just by spreading her toes! Imagine seeing the Kirino dip her feet in the ocean and turning it into a bubbling, stinky green mess with her odor and killing all the fish!
Kirino's big, pale, smelly, feet!