If you're concerned about them hiding some defects in the property, then you should have it inspected. 

Now if you have a plumbing defect (say  weak flushing toilet) then I would fix the problem not the effects of it. 

Truth is i WORK HARD TO BE THE FIRST GUY.we all carry defects of character.

Hello, I am currently in the process of doing some cosmetic renovations to my investment property and my contractor is constantly coming across bad mold, water damaged cover ups, and structure defects all throughout the units.

Tax sales are a way for a SELLER to get rid of a property that they can't sell otherwise; like toxic waste sites, mold problem, hazardous material problem, environmental problem, failed septic, failed well, encroachment, title flaw/defect, IRS problem.

Based upon the facts you've laid out, I do not see how you would have known, or should have known that this oil drum would be spilled by your tenant.As many have pointed out above, this analysis could change dramatically if you told your tenant to move it, you gave him permission to move it, or if the oil drum had some sort of defect in it and you knew about it and that contributed to the spill. 

Which of the covered risks in 2(a) do you believe covers the defect?

I personally prefer gutted houses, since I don't have to demo it, and all the defects will be obvious to see.I also look for small house on larger lot, in better area.

Then you present, in writing (and/or with supporting video) any defects that you're worried about being charged for or need fixed. 

Or some latent defects which couldn’t be seen unless someone lives there (toilet is running, microwave is broken etc)Stained carpet was there and they’ve seen it - no repairs!