What studies like this reveal is that people tend to think about evil as it if were a virus, a disease, or a contagion. Evil is an object that can seep out of Hitler, into a sweater, and, by implication, into you if you try the sweater on. Evil is sticky and contagious. So we stay away.
What we see in this example is how disgust psychology regulates how we reason about and experience aspects of the moral universe. Disgust psychology prompts us to think about evil as if it were a virus or polluting object. When we do this the logic of contamination is imported into moral discourse and judgment. For example, as noted earlier, we begin to worry about contact. In the domain of food aversion contact with a polluting object is a legitimate concern. But fears concerning contact might not be appropriate or logical in dealing with moral issues or social groups. Worse, a fear of contact might promote antisocial behavior (e.g., social exclusion) on our part.
The example of Hitler might sound extreme, but consider another study done by Paul Rozin, Maureen Markwith, and Clark McCauley. In this study the researchers observed that many people don’t want to wear sweaters previously owned by homosexual persons, or even lie down in the same hotel bed if a homosexual person was the previous night’s occupant. In short, just about any behavior judged to be sin could active disgust psychology, subsequently importing contamination logic (e.g., contact fears) into the life of the church.
Beck, pp. 25-26.