But it sounds like a combination of things could work

They are largely deceptive and misinformed...this is a volatile and unhealthy combination.

@Mark Eichenlaub I'd like to take a stab at answering your quistions... for the past 3 years my W2 has been a combination of managing a 700k sq. ft. portfolio of Class A commercial office space, industrial, retail and more specifically, right now 30 credit union locations. 

I live 25 minutes from an area with an extremely hot rental market combined with a housing shortage.  

@Jose Lopez:Repairs and CapEx are way too low. 15% combined is pretty safe.You're forgetting management (10%).Water/sewer is usually paid by the owner of a 4plex.Any other house utilities, like electric for common areas?

So combine party school with young students and that could have caused trouble for your uncle.

"AUSTIN, Texas — A new concept debuting in Austin combines condo ownership and short-term renting with the city's first high-rise homesharing property.Unit owners will purchase one of the 249 hotel-licensed condos with the intention of listing their unit on the Airbnb platform or independently or through Natiivo management, a new brand by NGD Homesharing.The development planned for 48 East Avenue in the Rainey Street District will feature 33 floors of fully-amenitized and furnished studios, one-bedroom and two bedroom units.

I will also strongly encourage you to consider local meetup with Freedom First Real Estate Investor’s Association, LTD (FFREIA) This local group has combination of new, couple of years and seasoned real estate investors.

I currently rent the home I live in because after crunching the numbers aggressively it is more beneficial to rent in my townhouse development here in NJ which was a combined property taxes and HOA fee of $900/Month before mortgage.

They can be a flat fee or a combination of the two.