Dogs and cats pee on laminate, hot-water humidifiers leak on it, kids start wet-mopping it when they spill something on it that they don't want Mommy to see, tenants turn off the heat when they go somewhere no matter what you write into the lease, and the stuff swells at the joints.

A family of 3 moved in and now the ceiling in the bathroom below has been leaking off an on.

Am I going to replace the cast iron plumbing even though it isn't leaking?

It just took some detective work to find this opportunity and track down the owner that had left several years ago and wanted nothing to do with property.

Another weirdness that you may or may not face...many of the homes were continually having big wet spots appear in/on the slabs, hundreds of people, were calling leak detection services, thinking an underground plumbing leak was causing these mystery wet spots.

If it's an older building surrounded now or in the past by mature trees with serious root systems, there's a chance the main sewer line to the stretet is leaking.

I don't like being near storage facilities or dry cleaners because who knows what hazardous materials have leaked into the ground and spread. 3.

I uncovered a multitude of issues (mainly cosmetic) but I have a couple of big ticket maintenance issues remaining - a slab drain leak (not supply) which was recently discovered and the home appears to need slight leveling (door jambs tight, small gap on brick outside). 

The culprit was a leak coming from a pipe in the crawl space below that other owners unit.  

The water usage was different every day indicating that it was not a water leak and abruptly went to zero on 9/20.