According to a conversation with Erik Nording that confirmed my theory, one of the reasons that you see the high grade Dannish bent pipes drilled higher than the bottom of the chamber is to allow the moisture a place to go out of the way of the draw, so it won't gurgle. Bents just create more turbulence than straights because of the bend. The Danes even sell a rock thing that fits into the bottom to allow you to smoke all of the tobacco, instead of losing some to being too wet. Nording has one...
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However, nsfisher is right, idle. The harder you draw, the more turbulence you create. Think of the stem as a condenser tube, as in a moonshine still with all of the copper pipe or an air conditioner. The harder the air flows through the tube and the cooler the tube is, the more moisture that is pulled from the smoke, which naturally contains water as a byproduct of combustion.
Drying the tobacco won't help with moisture in the stem. However there are a few blends that I dry out completely to reduce the bite and bring out more flavor. Brian Levine suggests this for Va and VaPers. However there may be some blends, as Bigvan says, that would loose flavor.