What you don’t know or check, can come back and bite you in your estimating & repair.  

He doesn’t estimate prices for repairs but flags needed repairs mercilessly.

-no vacancies-no repairs-no maintenance/capex? 

Lets assume that you run your numbers, and after accounting for projected expenses like vacancy, repairs, capex, management etc, you think the deal will bring you an average of $300/mo.

Do I have to repair it no matter what?

There are a lot of extra costs that go with home ownership-property taxes, repairs and maintenance, etc. 

You’ll want to have your numbers in order—this means understanding how much the property could sell for, what repairs might be needed, and what kind of offer makes sense for you.When you do contact the homeowner, be upfront and personable.

It is an older building, early 1900s, and I can foresee some major repairs coming within a few years if not sooner.

I went on the Thumbtack website  and it mostly seemed to cover home repairs. 

With 30% down your options are thousands of lenders.Why is it unwarrantable- master policy not enough coverage; low occupancy rate; HOA reserves; cannot be rebuilt or repaired; pending lawsuit in the less than 10 year after built for construction defect; flood zone with no flood policy...?