For example, I once walked away from a deal in Austin becaus rents lagged behind the crazy property appreciation there.You mentioned employment levels and income-to-rent ratios... great calls.

It's written into the lease that tenants must deposit their rents into that particular account (either by online bank transfer or by walking in a check/cash); I do not collect rents directly, nor would I if anyone asked.

I'd like the building to be within 10 minutes walking distance from a Brown Line L stop, ideally in Lake View, North Center, or Ravenswood.

I've had several "deal killers" who gave me numbers and walked a few OOS properties for me. 

So you put that up and you can do your inspection ( sale is not subject to it) and then do your sewer scope if its bad retrade or walk away far cheaper to lose 1k than get stuck with a 15k sewer line repair just the cost of doing business.

Run, don't walk away!

Finding some sort of value-add aspect or buying at a discount means you either create or walk into equity, which protects you.

I dont believe in ever losing money and lean towards the cash flow model, but recently I walked into a property with maybe $100.

I would also suggest that you find a meetup in your area of real estate investors that actually does BRRRR deals and will take you on a walk thru of one of their deals. 

Quote from @Aaron Fuller: Walk away.Rents could "likely" be raised to $8,000?