When I moved in this house had been a rental that the owner overpaid for and was dumping after his tenant passed on - sheet vinyl flooring, fake wood cabinets and Formica countertops, builder-grade everything. 

I’m closing on a great 12 unit next week that they brought to me before putting it on MLS and they have promised to keep the deals coming. 

I would not call that positive ROI, since I don't see how you can calculate a positive ROI with a negative cash flow (unless you factor in property appreciation or other yet to be fulfilled promise or subjective idea).

Here's my plan: I worried I don't have the bandwidth to actively own the asset class I'm interested in (10-to-30-unit buildings in emerging markets), so I'm doing some deep market research to identify a handful of really promising markets and connect with locals active in those markets.

The one with cash may have horrible credit or a checkered past that they are trying to distract you from with the promise of cash in hand. 

Additionally, a promissory note is the document which details the amount owed, interest rate, and the terms of your promise to repay which the state will assess a tax of $.35 cents per $100 of the face value of any promissory note. 

Lots of people sell snake oil, fake, concocted balances that are just guesses.

Here's the link i just posted about, but now the tenant gave me a vaccination for her dog 5 years ago and edited the page to make it look like it was for the cat.https://www.biggerpockets.com/forums/52/topics/727162-v...

Also it is 100% crystal clear to me that it is never disclosed to the homeowner that you will probably have to pay off the outstanding balance out of net proceeds when you sell, assuming you sell to a home buyer getting a normal mortgage, they are always shocked and aghast and insist that the solar salesman "promised" them something different, and as conveyed to me via the Realtors they want me to "look into it" (you want my magic crystal ball to help me parse the exact words of the non-binding irrelevant verbal statements of a door-to-door salesman who was speaking when I was not present?).

Fake it til you make it right?