The front door was extremely dirty. Covered with fingerprints and smudges, the door and its frame showed layers of dirt and smudges when the rest of the apartment could have passed a white glove inspection. We've seen this many times before, as doors and their frames are places we always touch but seldom think to clean.
All it generally takes to clean painted doors and frames is a damp cloth. A light once over and frames and doors can clean up to look as good as new. Also, don't forget similarly-overlooked high-use zones like light switches and the wall surfaces around them.