Code cleaning is a major way I get into a project. The "cleaner" it is (in a subjective way that appears clean to me), the more motivated I am to do things with it. The more I've cleaned it, the more invested I am in it. Ideally, I wouldn't care how clean something was and would just go at it, but I think I have to accept the motivational effect of cleaning code at this point. If I'm cleaning code, I'm more likely to do something interesting with it.