I know a ton of people do not believe in washing their belts. I have never seen a person loose their skill because their belt is clean. Please wash your belt/obi with the rest of your GI/Dobok/Kimono, nobody wants to cross paths with whatever bacteria might be lurking around in your unwashed belt. Just think about all the sweat dirt grime, and even a minuscule amounts of blood from tiny scrapes, drool, snot, even in tiny amounts that nobody realizes is even flying around.