how do you know an area is re-gentrifying vs. deteriorating?  

In general if a REI is buying cashflow positive real estate and their financial situation hasn't deteriorated since they purchased their primary residence, it's usually just the down payments that limit their ability to get additional mortgages. 

Of course, the standards were much lower, and with minimal upkeep, they deteriorated so much, that they were sold to private developers 3 decades ago.

Additionally, there is a lot of deferred maintenance and deteriorated property grades. 

Sounds like they could be picked up at a discount since there deteriorated and vacant.  

When the neighborhood deteriorates. 

Lath and plaster was deteriorating and powder.This is a frame construction.

Another consideration is the deterioration of the commercial office space market, as the dust settles and investors reassess portfolios, it is possible that the interest and demand for residential income producing properties further increases.According to the association of Realtors a 4-7 month supply viewed as a healthy balance between supply and demand.

But he seemed to want full $/ft & rent for the deteriorating "handyman special" shack in the back.. so I just couldn't do it.

We missed you and Justin at the last meetup at the beautiful Lake Chalet last month (or is my memory deteriorating..?).