Even hairstylists disagree about how long to go between shampoos. Frédéric Fekkai thinks most people look best if they wash their hair everyday; others like Chris McMillan insist that to keep hair healthy you should cleanse a few times a week at most. So when I met the perfect-haired Kim Kardashian recently, I asked for her take. “Hair doesn’t need to be shampooed every day,” Kardashian said. “I do it every two to three days. But if I go longer than that, my hair can become unmanageable. After [sister Khloé’s] wedding, I went five days without shampooing—which is a very rare thing for me—and it was pretty gross.” What about you—how long do you think is too long to go without shampooing?