I had suspected after my limited online research that the tenant might be responsible for a least a portion due to the clog and lack of informing me the toilet was not functioning properly.

In order to get homeowners insurance, the roof, plumbing, electrical, and HVAC usually need to be functioning normally and have reasonable service life remaining.Will the property appraise for the purchase price to the end buyer?

There are some skills that I suggest every homeowner learns in order to avoid high repair bills (in order I usually do them):-Fix minor roof leaks & repair siding/exterior-Fix water supply leaks with compression fittings or hose clamps if needed-Install lights, replace bad receptacles, switches, or breakers-Install electric water heater if needed-Fix subfloor & sturdy up framing if needed-Fix/replace windows/doors/glass and install locks-Drywall/mud, brush&roll paint-Install floor (floating/tile) and cut/install trim-Install toilets/sinks/cabinets/faucets-install mini split units if no functioning ductwork

If you're local, as I am, it's also a great idea because you'll call in the same lawyer when an eviction starts taking a weird turn, and that lawyer will function more effectively if s/he was the one that taught you how to do evictions in your area.

They miss out on the opportunity to further increase their return on investment, raise property values, and to create a beautiful functional home instead of just a house.

They miss out on the opportunity to further increase their return on investment, raise property values, and to create a beautiful functional home instead of just a house.

They miss out on the opportunity to further increase their return on investment, raise property values, and to create a beautiful functional home instead of just a house.What type of investor are you?

They miss out on the opportunity to further increase their return on investment, raise property values, and to create a beautiful functional home instead of just a house.What type of investor are you?

Cosmetic upgrades will have the biggest impact on value for appraisal purposes, assuming the existing mechanicals are functioning well.I would say look at some homes that have sold for 115k - 120k and see what kinds of upgrades they had. 

I don't know how it will affect resale value, but since you would still have garage space in the primary home, the functionality of the home will only be improved.