Look for components you can separate out and write off immediately (appliances being one that I see missed a lot). 

In PA there are 3 components to the yearly taxes, municipal, school and county. 

Now, some will say you're over leveraged but here's the second trick: there are essentially 4 components to negotiating the terms on a note - price, monthly payment, interest, time.

@Alexander BurkardThese two components dont have to happen in any particular order.I do both at the same time.

What I like about the property:- major components are in good condition.

Production for components of many electronic products is done in China. 

Seasoned investors are going to look at a retail property or other assets classes and as part of DD look at what is reasonable as a history for a property and how to validate the credibility of rents and others components of a lease.

Still, what I do (which let's be frank, is still somewhat trash) mirrors other comments: square footage, age and life of components, and vacancy rate based. 

You left out the rehab portion which is a major component.

There is the relationship component to it, and it might be short sighted to cut him out, even if you can, if there is longer term opportunity to stay on his good side.