Criminologists while studying urban crime have come up with a concept they call the "Broken Window" theory. Essentially as you walk the sidewalks around town and note broken windows your initial impession upon seeing it is that someone will replace the glass and fix it. Upon seeing the window remain broken day after day you conclude that nobody cares about this area and it is not the nicest part of town. Hence this leads to more damaged buildings, sanitation problems, and increased crime. The city of New York had a large problem with broken windows in the late 1980's and was one of the largest unsafe cities in the U.S. With focus on these broken windows and other areas of neglect, the city turned itself around in the 1990's and now is one of the safest large cities.
Likewise, we can extend this broken window idea to home maintenance. Deferred or neglected home maintenance by a homeowner may be acceptable while the homeowner lives in his own house. There may be valid reasons for it like financial, illness, can't find the right handyman, etc. Most of the time the reason is focus and discipline. That air conditioner unit needs replacing, this is the year we need the new roof, that trim needs painting, we really need to remodel these bathrooms, the carpet looks pretty worn, etc. But eventually you have to pay the piper.
A REALTOR in consultation with a seller in preparation for selling the home often delays the listing date to get the house in showing condition. This may take weeks and several thousands of dollars. Some sellers balk at getting the home in tip top shape and want to sell "as-is" but they are doing themselves a disservice if they go that route.
Paying attention to any "broken windows" along the way and maintaining your home is the best way to protect your investment.