I suspect maybe something like Hagerstown or Cumberland, which yeah are Class D like markets with declining populations, high drug problems, no strong job base which leads to non paying tenants.

A portion of rent goes to the purchase price which is on the top end of market value. 

I guess with certain markets its achievable!

My main job is running my investment holding company, so I'm familiar with public and private market investments but new to RE. 

It's a free market. - You will finally get a tenant. 

Quote from @Marc Zak: In the market where I live (San Diego), appreciation has been strong and many predict it will continue to appreciate in the long term.However, with current interest rates (6% at best) and property tax (2%), the annual cost burden is 8%.Am I correct in saying that appreciation has to be above 8% annually (plus whatever my maintenance and vacancy costs are) for me to make any money in this scenario if the property is cash flow neutral?

Just like any of the investment strategies here in BP, they need to evovle as the market and housing landscape evovles.

Until the lease ends and then the legal notice time in your market has passed.

I would recommend joining local facebook groups of hosts (if they exist) for markets you are trying to get in to. 

Zillow Rental Market Stats: It gives you an idea of how a zip code is performing, even down to the bedroom count.