I read an article about this a while ago, about a woman who doesn't wash her hair on advice from her hairdresser. She said it took about 10 weeks to get 'naturally nice' but now it really doesn't need it. My brother hasn't washed his for years, and doesn't use any products in it. I'm surprised by how nice it feels! I'm not game to try it myself though, my hair goes pretty feral after a few days lol