Shoes make feet smell, the whole world knows that. Actually no, many blame the foot not the shoe. Aversion therapy is a behavioral treatment intervention based on the principles of classical conditioning and behavioral psychology. It is sometimes referred to as conversion therapy or reparative therapy. The goal of aversion therapy is to eliminate bad habits, self-destructive behaviors, or other undesirable behaviors (e.g. nail biting or alcohol abuse) by pairing the behavior with an unpleasant stimulus (e.g. medication-induced nausea or an electrical shock). The assumption is that the problematic behavior is a learned behavior, and as such, can be “unlearned” or changed with proper “conditioning”. Remember Pavlov and his salivating dogs? The conditioning that occurs in aversion therapy very is similar in many ways to Pavlov’s famous experiment. By ringing a bell just prior to feeding them, the dogs became conditioned to salivate at the sound of the bell. This is because they learned to associate the sound with food (if you have pets you’ve likely observed something similar!). Olfactory or gustatory stimuli – The term olfactory pertains to the sense of smell, while the term gustatory pertains to the sense of taste. Used far less frequently than other aversion therapy methods, the use of these stimuli involves exposure to an intensely foul odor or taste, such as ammonia (one of the most frequently used olfactory stimuli), each time the person engages in or imagines doing the unwanted behavior. Source of the above is this website https://www.addiction.com/a-z/aversion-therapy/ So that's it, the whole shoe wearing population of the world has been exposed to Aversion therapy, foot haters explained.