He said he had repaired the AC himself and used $20 of materials and could he deduct it from next months rent.  

@Chris Chesser were you able to get the bonus material for @Scott Trench's book?

If you actively seek out NPN's and materially participate in the workout process, the IRS might opine that you're running a business at that point, not acting as an investor.

Sometimes it's ok to just leave asbestos alone.Here's one source I found:Is the asbestos in your home in materials that are deteriorating or likely to be disturbed, perhaps through future remodeling?

Maintenance costs are low,  mileage tolerable.If you are going to self manage you need to be able to haul material and not have it exposed to the weather.

#@Until we noticed all newer material of floor joists and subfloor directly over the tub.

What I see that can become an issue is when investors want to do things like do part of the work or buy all the materials.  

If he says it's for materials, offer to pay for the material directly.

If the mold penetrates the wood or drywall too deeply, you may need to replace those materials.

(143-210)Material list (Exterior):Base – Garden Wall (Behr PP 730D-4)Trim – Cornerstone (Behr PP 330E-2)Accent – Intellectual (Behr PP UL260-2)Front Door – Roasted Pepper (Behr PP 180D-7)Door Handle – Kwikset Smartkey (754-825)