Imagine opening your front door, still in your pajamas, on a frosty Swiss morning, only to find a man dressed entirely in black staring back at you. Charcoal trousers, top hat, and boots, a little broom and dustpan peeking out of his bag. He waves an official-looking document in the air and insists on entering your house. A little bemused, you wave the chimney sweep in. Such encounters are common in Switzerland, where these men and women in black are jokingly called the “chimney sweep mafia”—“mafia” because they seem to…