In fact, it was never cleaned, AND we lived with a non-draining tub for over a month! 

Oppose to a single family dewling draining your profit margin. 

The IRS has seen a noticeable drain of their auditors who had the most longevity and are now trying to cope with mediocre, second string employees.  

These two things cannot be said about rent, which is just money down the drain into somebody else's pocket every month.  

As for inspecting the plumbing, just depends on how old the house is, how long has it been sitting vacant, through the winter, what kind of water piping does it have, and what type of drain pipe does it have, just to name a few.

This can be an emotional drain on you.

Is the sink not working because you have clogged the drain with things like grease or leftover food? 

I always add drain pans if there is no floor drain present.

Yet there is the poverty and lack of lower end jobs that is a drain on the city.If you understand the city there is tremendous opportunity for investment. the ratio of rent to price is extremely good for investors right now.

A good preventive maintenance measure is that every time you have a vacancy, drain the hot water heaters.