caption: Slide 4 of 11: Why it's dirty: When a vacuum filter hasn't been changed or cleaned in a while, not only is the vacuum unable to pick up as much dirt and dust as it should, due to decreased suction, but dirt also is blown back into the air and carpet by the dusty vent. How to fix it: Change or empty vacuum bags or canisters immediately after they become full. Wipe vacuum attachments, the hose, and the vent with either a damp microfiber cleaning cloth or a moist paper towel, double-checking that the vacuum is unplugged first. And make sure you're not vacuuming these things you should never vacuum.