It’s a great system provided you buy correct, rehab timely and on budget, find a quality tenant and can refinance quickly.  

Inspection quality and aggressiveness can vary among inspectors.  

While it may cashflow now, my concerns would be higher maintenance costs and tenant quality/stability issues that stem from the overall functional obsolescence that's present in a lot of Chicago's 100+ year old housing stock.

For investment real estate, besides the quality of real estate itself, such as location, construction, layout etc, liquidity is the key. 

The quality of life and time I could have spent with family and friends was instead spent laboring at my house being miserable and resenting the house in the end for what it took away from us.

Do you care about appreciation and house quality or do you just want "cashflow" properties? 

For example, when I buy a building in a "C" area, I renovate it to "B" or even "A" level quality.

Do some rentals just require the bare minimum improvements to get it rented or do someInvestors think it’s wise to go a little above and beyond in hopes for a higher quality tenant And better rent?

First, I think they would make the kitchens look a lot nicer and would in turn improve tenant quality / demand slightly higher rent in a competitive area.

@Jay Hinrichs and @Greg Dickerson, How can one find quality builders who will build for less than $110/sq. ft?