@Dave FosterTo be fair, I may have been a little broad in my interpretation. 

This is a very broad question.

I can tell you broadly that a lot of cash buyers avoid roof and foundation issues due to the cost and that they favor properties that require basic cosmetic repairs.

Ive always liked working in the mortgage industry and i understand the mortgage industry is very broad.

@John Dickerson  A very broad question but in terms of what you legally must provide as a landlord it comes down to how the laws of your state define "habitability" of a rental property. 

Im on the opposite end of the spectrum though.

Thats a super broad question.

"wholesale" is a broad term.

You can also look at reports from IRR.com and or www.marcusmillichap.com for a more broad overview of the market.For market cap rates look at the report put out by CBRE  "US CAP Rate Survey Advance Review 2018"

Create your own by adding an accessory dwelling to a single-family house, as detailed in this BP thread from California:https://www.biggerpockets.com/forums/61/topics/732543-here-is-my-adu-variation-to-brrrr-its-called-bra2xrrDC, Arlington, and Montgomery County have all updated their zoning laws in recent years to broadly permit ADUs within or behind owner-occupied houses.