Kaito normally had superb grooming, but when Kid went out on a heist, he took it to another level. It hadn't always been so – he had once thought that his normal, strenuous routine would be enough. But he had been mistaken, and a single dropped hair had been enough to convince Hakuba (if no one else) of his identity.
So now when he was preparing for his heists, Kaito took time for an extra shower, just to make sure. A little bit of hairspray helped to keep his hair in place (and he always made sure to use enough to prevent another stray from being dislodged – once had been more than enough), both on his head and on his body. He even made sure of his eyebrows and eyelashes with a special solution, the recipe for which he found, somewhat belatedly, among his dad's equipment.
Kaito never dropped a hair at a heist again, and he made double sure to never drop one while 'incognito,' either. At least not where Hakuba was around to retrieve it. Because one hair was bad enough, but two—Two would be enough to damn him.