Speaking especially to fellow California-based investors, viewing this excellent post as exposing "Baltimore specific" problems would be inaccurate. Based on my personal experience in other areas (Rochester NY, Toledo OH), you will find similar problems if you buy without adequate, on the ground personal research and/or simply rely on the standard out of state turnkey model on which to build your REI dreams.
It seems that people living in LA or SF or Orange County etc. see what appears to them to be ridiculous low housing prices and ridiculously high rents relative to those low prices and think that playing this arbitrage opportunity will be easy.
There are four facts that should not be overlooked.
One: The fact is that for every buyer who is blinded by $$$$$, there is a repeat seller who knows the market better than you do and who is not buying, but is selling to you. Who is going to win?
Two: The city leaders in these places do not represent you - the out of state investor - and do not care about your interests. They see you as an easy source of tax revenue and/or as a bucket of ready cash that's needed to bring its derelict stock of housing into some semblance of shape (e.g., lead paint laws).
Three: There is no such thing as a "landlord-friendly" state. Evictions are universally handled at the local level an, again, as an out of state investor, you have no friends in those local courts whose usually elected judges will need the votes of your tenants at some point in their tenures. Trust me. As an out of state investor, with a name that appears on court papers as "I make money off the locals LLC" you will get repeatedly home-towned no matter how good your local lawyer happens to be.
Four: In my personal experience, fewer than half the tenants in class B-/C+ and lower areas pay their "share" of the section 8 rent and seldom cover the utilities. If you are eager to go section 8 expect to receive the government's portion of the rent as full rent and to have to cover the utilities out of pocket even in the case of SFR's (in multi-units you end up paying water in almost all cases anyway). You might be pleasantly surprised by the occasional $100 coming your way from the tenant but I have found that to be the exception rather than the rule.
Bon chance