In places that have a job market collapse, that is where you had people leaving the state for other employment and they saw reduced rent rates and higher vacancy.

In our area septic lines can cost you $10K real quick if blocked by roots or collapsing.

Yes, maybe filing taxes yourself might be a little more difficult, or using a tax professional might cost a little bit more but a little more time or a few extra dollars every year to prevent a total collapse of your portfolio is more than worth it in my eyes.

Otherwise, their investment will collapse.

If it collapsed like that condo building in Florida, or the fire in California, would they cover you, against the claims from the tenants and their survivors?

If left unchecked the wall could eventually collapse inward with undesirable to catastrophic results.It may be possible to brace the existing wall to halt movement and/or support the building to allow that section of the foundation to be repaired/replaced.  

I approved the expense - in my mind picturing broken pipes and the ceiling collapsing if not done timely.I just saw the description of work today on PM's website:  "New p-trap, sheetrock, caulking"So, did I get ripped off, & can I or should I challenge the PM on the expense?

Short of catastrophe - i.e. the economy collapses so hard that people are living under the bridge rather than paying for a rental because they can't - you are always going to find people that would rather live in a house than live in a cardboard box. 

I think you're building a house of cards with highly leveraged, cash flow negative properties that will at some point collapse.

Also, these properties typically need upgrading/repairs that when combined with the purchase price will bring your total "in" cost much higher.Some investors have been successful finding properties that meet the 2% criteria during certain economic collapses, such as outlying areas of Phoenix and Las Vegas in 2009-2010.