Bubba, those commercial pipe sweeteners are a waste of money. Get some Everclear (or other booze), soak a pipe cleaner, and scrub out the stem and shank. Soak some into a wadded-up paper towel and scour the inside of the bowl too. Or, follow the salt treatment link that
Tommy provided.
Since I use 1 or 2 dry pipe cleaners after every smoke, I only need to do the full treatment thing every 4-6 months -- and, like
pstlpkr, I use cotton balls instead of salt.