Foot odor comes in four main varieties: sweaty, cheesy, vinegary and cabbage-y. That’s because of chemicals produced by the bacteria down there.
Methanethiol is a key component in the flavor of cheddar cheese. Acetic acid is a result of sugar fermentation — and is better known as vinegar. Byproducts associated with rot, such as propionic acid and butyric acid, can leave feet smelling like rancid cabbage. The most common foot-related chemical, isovaleric acid, is responsible for the smell we call “sweaty.” Our noses are up to two thousand times more sensitive to this chemical than the others, and many of us can recognize it even at the slightest concentration.