I used to host without password the schemes I'd like to play, mostly my own schemes or underground ones, but I often hosted or joined WxW, Intermediate and other popular schemes I like to play. When I want to test a scheme with someone or I want to play something very complicated that I already have someone to play, I usually put password.
Lately I'm not very active and most of the games I play are from cups or leagues (usually TUS ones) that my opponents have to insist to play with me or I need to make an extra effort to play. When I play, usually I enjoy the moment, though. Specially new interesting schemes and not the same old schemes like Shopper that I don't understand why people still play so much, even being a veteran.