The breaking point came when he had to take care of his parents, whose mental and physical health was deteriorating.

Look for tall grass, abandoned/deteriorating houses, etc.

The reason many are high yielding is often because the underlying fundamentals of the company are deteriorating and the stock price has dropped while the dividend has not yet dropped.

The life estate document also usually prohibits the LE tenant from "wasting" the property or allowing it to deteriorate.

In balloon framing you close off the top and bottom of the walls.Actually, there has been a fair amount of research (visit the Building Sciences Corporation library for one source) demonstrating that moisture - from external water penetration or air leakage (or, form the interior if open cell foam is used -  can frequently permeate the roof deck causing deterioration (rotting) of the deck itself and/or mould growth.  

It has what appears to be asbestos siding - I am not under contract, and this has not been definitively tested.There appears to be a bit of cracking going on, as well as some deterioration where the siding meets the eaves and the roof.

The regulations provide a list of situations where the unit of property is restored, such as if the expenditure (a) returns a unit of property that deteriorated to a state of disrepair (and can no longer be used for its intended purpose) to its ordinarily efficient operating condition or (c) replaces a part or a combination of parts that comprise a major component or substantial structural part of a unit of propertyIf you had just patched the crack that would be repair.

It was usually used with non sanded grout which deteriorated over time.

Letting your properties deteriorate will result in lower tenant quality. 

Yes it is mostly from depreciation, but also as a result of repairs and maintenance eating up profit - which could be deferred but at the risk of deteriorating the properties.