I had to fix the A/C or heating from time to time, but overall, it was gravy.

You also need to consider equity buildup and loan paydown, tax benefits, rent appreciation, and potential property appreciation (don't bet on this or anticipate it.

Bet on yourself.

Is it because of investing in some C or D neighborhood, or more on the macro economic or demographic?

If you are using a buy and hold strategy, know that it is more likely that you will not get your rent or rent on time in a C- or below neighborhood.

If you're renting out a C or D class property, I think the credit minimum would be much lower than an A or B property.

@Selby Johnson sounds like a Class C or D area.When investing in areas they don’t really know, investors should research the different property Class submarkets.

***Only exception is if an owner has plan & funds to reposition Class D to Class C or higher.https://www.biggerpockets.com/forums/776/topics/960183-what-they-dont-tell-you-about-cheap-rental-properties?

I feel like from the multifamily choices I have found the choice is either to be a slum lord  and cash flow big or no cash flow and bet on capital gain. 

Jolene,If I had to bet, I would bet on YOU...