In october, when the Canadian air starts drying out, the men flock to Sandy Skotnicki’s office. The men are itchy. Skotnicki studied microbiology before becoming an assistant professor of dermatology at the University of Toronto. She has been practicing for 23 years, always with an eye to how the environment—including the microbial one on our skin—affects health. “I say to them, ‘How do you shower?’ ” she told me. “They take the squeegee thing and wash their whole body with some sort of men’s body wash. They’re showering twice a day because they’re working out. As soon as I get them to stop doing that and just wash their bits, they’re totally fine.”