I clean my bong out after every smoke sesh...my bong is nice to me so why not be nice back and give it a cleaning =).

The best way to clean it (IMO) is to get a cup of rubbing alcohol and a tablespoon of salt, put it in the bong and swish it around...easy to do and works GREAT.

I would suggest you put fresh water in your bong every time you smoke...it gives it a cleaner taste and is much more pleasant.