After seeing the place, taking photos, and calculating the repairs that needed to be done I spoke a little more with the owner to find their motive for selling and their rock bottom price. 

Any after rehab photos?

Are their listings detailed with good quality photos?

I keep a nominal amount of free cash in a personal checking account, and about $15K in a checking account for business and real estate related expenses.

The interior photos were... eye opening.  

If you haven't seen this for yourself or photos, I'd also suggest doing that.

In the photo it looks like replacing missing siding and new paint should be a higher priority to increase curb appeal.

The Zestimate is not a good substitute for proper valuing of property; it might be useful for relative comparisons to see if property A should sell for more than property B.A few years back I read something that criticized Zillow; it showed actual photos of two houses located close to each other.

Now you will not know from a picture if you go through the photos (if it's not private) you possibly connect dots.

These are awkward for most parties involved, and could cause problems if the seller is a talker and says the wrong things.Imagine the best scenario, you hire a home inspector (a standard practice in normal real estate transactions) to come in and compile a 65 page photo-filled report talking about the condition of the property and listing every loose door knob, evidence of rot, etc.