I picked up the properties for a heavily discounted price (because they had sat on the market), and had no problems finding highly qualified (and high-earning) tenants that made the place cashflow right out of the gate.Another example: I once bought a property in an A class neighborhood that had an awkwardly-placed stairwell inside the front entrance, which turned off other buyers.

Many listings that I’ve actually walked through state a mother-in-law apartment but there isn’t a separate entrance to the apartment or there aren’t washer and dryer hookups even though it’s stated.

However, a few other key factors to help you filter through:If ceiling is at least 19 feet you can add a 2nd floor and basically double your Sq Ft capacity (course you'll need to add an elevator)What to do about the Parking Lot - this can be for "Boat & RV Storage" or perhaps use the opportunity to expandAccess Points for easy entrance/exit.And the major wildcard is the city Planning & Zoning - is it currently zoned for Self Storage? 

I am really thinking about moving to places like Oklahoma City, Indianapolis, Little Rock, Memphis because of the returns I am able to see on a consistent basis (thinking 80,000-100,000 homes)I also figure because I would owner occupy, I would get favorable terms on a multiplex that could cash flow much more strongly and give me an affordable entrance into the investing world. 

Some light construction/framing is needed to properly separate the entrances at the back of the house.

I have made offers with a contingency that I would need to gain entrance and inspect the house. 

I noticed that other houses do not have walkways, but some have the driveway close to the entrance.

@Mark BertoniWe are in the process of purchasing a building from the 1920s which is "original": 5-circuits per unit, all wiring (save perhaps a couple of new laundry hookups) are K-n-T; the building has a 200amp entrance for six units :-O   The re-wiring is handled by either vendor or purchaser - it's negotiable - though vendors are usually aware it is present and not inclined to update it.  

If it's not a duplex, maybe it's a house with a separate entrance/basement.

Do you already have primary and secondary entrances to each unit, or will you need fire escapes?