
There are a lot of windows in the building, but you'll never know who live in the apartment. You have not much time to identify the person, whether it's hostile or kind. Deal with scum by throwing a pie in their faces.
Get a pie and look attentively at the building in front. Time to time you will see the citizens of the building in windows. Identify them and throw a pie towards hostile units. They also have pies, which they will use to disable you. Throw a pie before they do and clear the floor. Complete all floors and clear the building from the presence of scum!