The design of a dryer is pretty straightforward. The clothes get tumbled in hot air, and the wet air is vented outside. The lint trap does most of the heavy lifting by catching all the fibers (and pet hair) that come off your clothes, but the stuff that gets past the lint trap lands in the dryer vent. So even if you clean the lint filter after each load -- and if you don't, tsk tsk -- you'll need to give your vent a thorough cleaning every year or so. Why is this so crucial? For one, lint buildup can create a fire hazard. It also forces your dryer to work longer to do its job -- time that you’ll be waiting. And finally, inefficient drying equals more money out of your pocket.