Stage three: Scrub the Vent Deal with Wash off the outer vent go over using a cloth with warm h2o plus some dishwashing liquid to get rid of Grime, dust, and soil. Rinse with water and reattach the vent protect.How Often to scrub a Dryer Vent Depending on how often you use your dryer, follow the techniques below to scrub the dryer vent at the least