Like deferred maintenance, (bad roof, worn out water heater/AC Unit, warped flooring, water damage) etc, unpaid utilities,  unpaid taxes, a second loan, unpaid HOA fees, a bad pool, bad reputation, sometimes squatters, sometimes they were drug houses, and so on.

My rental condo in Asheville, NC was spared damage from the flood, but when the city finally turned the water back on a few days ago, they somehow overpressurized and blew out a fitting inside a wall. 

Purchase price: $275,000 Cash invested: $45,000 Sale price: $400,000 Contributors: Adam Schooley This townhouse, which had gone through probate, suffered from significant water damage to the drywall and required updates throughout.

Purchase price: $275,000 Cash invested: $45,000 Sale price: $410,000 Contributors: Adam Schooley This townhouse, which had gone through probate, suffered from significant water damage to the drywall and required updates throughout.

If you think there a leak have all tenants not use any water and find the water meter outside.

The licensed plumbers do not get permits for water heaters, I have never heard of one being red tagged solely for not having a permit so I do not get permits (and know no one that does) for swapping a water heater.  

This shall apply to single glazing and each pane in multiple glazing.Exception: Glazing that is more than 60 inches (1524 mm), measured horizontally and in a straight line, from the water’s edge of a bathtub, hot tub, spa, whirlpool or swimming pool or from the edge of a shower, sauna or steam room.

What happens if the water service line has to be replaced?

On some older properties where perhaps you have one water meter for 2-3-4 units or one gas meter for 2-3-4 units, or units that share hot water, something like that the owner might pay. 

Purchase price: $275,000 Cash invested: $45,000 Sale price: $400,000 Contributors: Adam Schooley This townhouse, which had gone through probate, suffered from significant water damage to the drywall and required updates throughout.