The water cause a deterioration in the lining of the pipes to where now Lead leeches into the water even though the corrosive water is no longer being used.The solution requires replacing the pipes not just switching back to a good water supply.

The husband had passed away and the wife bought a new house and the beach house had sat for five years and started to deteriorate. 

At 1%, that's an estimated $70,000/year over your $7m portfolio for deterioration of your furnaces, roofs, floors, appliances, plumbing, etc.

I have also struggled with tennis courts due to damage to nets and posts, deteriorated surfaces and trouble w/pooling water. 

Proper preparation and pointing is recommended to avoid further deterioration and possible water penetration.

I've looked at several homes for sale whose owners allowed the satellite to be installed on the roof and all of them either have some kind of hole or is deteriorated around the install.

The vent stack and/or service mast boot flashing is damaged or deteriorated.6.

I'm also worried because it seems like the town makes it so difficult for us to invest in improvements that the town as a whole will deteriorate over time.Are there any other North Bergen, NJ landlords here able to share insight?  

For the door we have had for example issues with older houses and screen doors where hinges pull out because of wood deterioration but this does not happen on entry doors. one prevention solution is to put a door stop ( a wall or post ) so it cant go that far.

We had many incidents of tenants flooding their entire living room having their balconies deteriorate due to negligent behavior.