.), painting the walls and ceiling with an oil-based primer to ceiling in the remaining tar, painting, and installing new flooring. 

An in ground oil tank for instance can be a considerable liability. 

I have, however, been attempting to DIY paint the kitchen cabinets and have spent over 8 hours just trying to clean the cabinets of all the dirt, grime, and oil built up over the years.

Oil is $80 right now and some people predict $200. 

@Konstantin BoubevI used a company called ERC for an oil tank removal twice.

That equates to a better return on investment.I learned how to change the oil on my car, did it once, and realized it is not worth my time and effort.

Sell some snake oil elsewhere.

Basically an informal audit of ones portfolio.This could be as simple as creating a few benchmarks (specific ratio of expenses, total PM fee ratios, vacancy rates and duration,etc)As much as one could assume they have a well oiled portfolio, an outside investor could find areas of improvement.

Otherwise, anything with a wet cloth pad will get dirt and oil stuck in the pad, which then gets spread throughout your floors as you mop.

The land, zoning, waste disposal system, in ground oil tank, elevations, liabilities, encumbrances, lot size, setbacks, and other issues that may have impact on an investment decision and any value add opportunities or lack of.