Hi! windows gets greasy and tends to attract more dust, what if your cleaner has just cleaned your window's glasses and your kid puts a dirty hand mark on it again? Cleaning and maintaining cleanliness are two different things. Just develop a habit of maintaining cleanliness, and when it is needed to be cleaned, spray a little vinegar solution and rub and wipe off with a cotton cloth. Now, rub the surface with crinkled newspaper to bring back the shine.