Most of them are in undesirable neighborhoods.

DF was became effective in Jan of 2014 and basically made it very difficult and highly undesirable to hold mortgages for tenant buyers.

My best deals come from undesirable properties.  

With that being said, my current predicament is this: It seems very difficult to start investing in LA because the only multi family homes under 400k are in VERY undesirable areas, but this is where my job is so I can't leave town for a more desirable place to invest in real estate. 

Due to the popularity (lots of people) it made the area undesirable to me.

The state of the economy and supply vs demand is making investments more expensive; however I believe investing in markets that are still slow at this point or have ample supply is a risk - they will drop faster and have higher vacancy rates in the next slow down cycle.Investors want motiveated sellers and buy cheap - but think about it, why would you want to be in the shoes of the guy who ownes something that is so undesirable that you have to discount it to find a buyer.   

The Poverty Kid turned Real Estate Investor journey was not easy 👇🏃🏾‍♂️ From dodging gunshots in the New Orleans Housing projects as a kid to 🛏️ Frugal living in an undesirable apartment to🏠 Purchasing a starter home as a first-time homebuyer to👨🏾‍💻 Buying & Self-managing my multiple rental properties to 🗣️ A speaker for BiggerPockets!

Originally posted by @Robert Howell:I believe the borrower cashed out the property.I took this somewhat vague statement to mean that a foreclosure of the investment property was unavailable/undesirable for whatever reason, which is why the OP was attempting to look to other assets to collect on his note.

Undesirable size and floor plan.

For example, North Philly by Temple University is a wonderful place to get into; however, the boarding neighborhood can be a little undesirable and breaking into the Temple market is difficult due to higher cost.