I keep my pieces pretty clean because I don't like the taste of dirty goop, or the idea of whatever lurks in the bong water. In fact, when I think of it, I dump out the bong after use so it sits there dry, and doesn't get nastier. It also goes through the dishwasher often.
I have a little jar of alcohol I soak my slides in between uses so they stay unobstructed and hit better.
IMO, it's a great idea to have good bong hygiene!