Mom and Pop owner with zero records

[Sam Epperson]

I have a deal for a Mom and Pop owner who owns many properties. All of his financials flow into and out of one account. He has zero records for individual properties. He built them in the early 90's and has owned them since, with repairs only being made if the local housing authority has legally demanded it. They are in need of updates.

Even in their poor condition, they are being rented at 85-ish% market rate, with 15(?)% vacancy. No actual management, lots of deferred maintenance, not capturing fees, etc. 

I can estimate expenses based on comps, and he has a "hand written rent roll" from september. 

This is in a strong rental market in a college town.

This is textbook "opportunity" property. 

Is it, though?
I've had 3 experienced pros look at my underwriting and effectively say I can't bring investors much more than 15% IRR on this. This is at my most conservative underwriting.

Is this not a return that investors are looking for? Am I not finding exactly the type of property and owner they told me to find? Is this not a great market? 

I'm getting stressed out because the same people who are telling me to look for one thing, are the same ones who are saying that (when I find it) it isn't right.

What am I missing?

[Don Konipol]

@Sam Epperson

Lack of historical financials takes the lower cost financing off the table and leaves only high priced money available, with larger down payment demands. Further, deferred maintenance issues aren't always apparent so costs are hard to estimate, increasing risk. 15% ROI mentioned may be top end estimate, so return could be much lower.