No one wants to admit to sniffing their dog's paws but let's just say one day you happened to get a whiff in passing and you noticed the distinct smell of corn chips. This has happened to me...on more than one occasion...by accident of course. According to a Q&A on dogster.com:
Bacteria and yeast naturally reside on the skin of all animals, including cats and dogs. The feet of both species contain many folds and pockets, such as the areas between toes and the spaces between the foot pads. These areas have increased levels of moisture and decreased air circulation at the level of the skin.
The increased moisture and decreased air circulation in these environments enables the resident bacteria and yeast to proliferate exuberantly. These micro-organisms give off odors, and I suspect that they are the cause of Frito feet.
Frito feet? I've never heard it called that. Sounds salty but delicious...