2:16 p.m. on June 16, 2010 (EDT)
hmmm, from several posts above, it sounds like there are a few concepts relating to humidity, water vapor content, and related topics that are not well understood. Well, I knew that from when I used to teach survey physical science (which included a section on meteorology) as one of the "bread and butter" courses (gotta generate income for departments like Physics, Astronomy, and such that don't have a lot of majors).
Anyway, The perceived "dryness" of the air (aka "relative humidity") is dependent on two things - the amount of water vapor in the air and the amount of water vapor that the air can hold when saturated. The rate at which something (like wet clothes and wet sleeping bags) dries depends on the relative humidity. The amount of water vapor the air can hold when saturated is dependent on the temperature - warmer air can hold more water vapor.
So - heat the air, and the relative humidity decreases, which increases the evaporation rate and shortens the drying time. (yeah, everybody knows that).
When drying off in a tent, there is another factor. If the tent were sealed (a tent made of purely plastic sheeting, for example), heating the inside of the tent lowers the relative humidity (since the holding capacity of the air increases with temperature), which would allow the liquid water in your clothes to evaporate into the air faster, spreading the water as vapor throughout the tent (I am ignoring how you heat the tent to avoid the "trivial" issues of oxygen depletion, carbon monoxide buildup, lighting the tent material on fire, etc). The relative humidity gets lowered to, say. 50%. Aha! you and your clothes are now dry, so turn off the source of heat. Tent walls are not very good insulators (whether my hypothetical plastic sheeting or nylon), so if it is cold outside (say, 40 deg F), the inside air will cool down more or less quickly. This drop in temperature increases the relative humidity, which means that the water vapor will start condensing back to liquid, and you are wet again. Some here may be old enough to remember when we used to use plastic tube tents as a substitute for paying big bucks for tents - though that practice was abandoned after several deaths from suffocation, notably a couple of them in one night in the Mammoth ski resort parking lot. On a subfreezing night, the walls would become coated with a layer of ice, and on warmer nights, the walls would become covered with condensation that would rain back on the occupants.
Most tents are made with the main body of very breathable nylon, or perhaps mesh in the currently fashionable version of "3-season" tents. So the heated air will flow out through the walls of the tent (or the uncovered mesh door of a real 4-season or expedition tent). The outside cooler replacement air is of lower water vapor content (hence lower relative humidity), so you can actually make progress in getting and staying dry.
In areas of 90/90 weather (such as Mississippi where Barb and I lived for 10 years, or the Gulf Coast, or tropical climes), raising the temperature enough to drop the relative humidity creates a losing situation. Luckily, most of the time even in rainstorms, the relative humidity is much less than 90%, often no more than 50-60% (that is, until the rain stops and the sun comes out, evaporating all the puddles and running the water vapor content up to the 90+% level again).
Yeah, candles help some. But they do have the same problems of any flame - open flame source increases risk of igniting synthetic materials, especially silnylon; flames from candles and stoves deplete oxygen, replacing it with carbon monoxide and carbon dioxide.
Standard disclaimer: DO NOT DO THE FOLLOWING DESCRIBED PROCEDURE - professional mountaineers in desperate situations in blizzards only.
It is possible to safely use a stove in a tent. As Jim S has posted from time to time, using a stove in the tent increases the rate of drying of clothing. However, the tent must be well ventilated. Risk of serious injury or death is high (example, the oft-cited, ill-fated Wilcox expedition on Denali in the mid-60s - read In the Hall of the Mountain King for details, but basically, while cooking in a tent and refueling a stove with a second one operating, the resulting ignition caused the tent, a sleeping bag, and a couple of down parkas to vanish in about 10 seconds).