You may need to also prove the soil is not contaminated by doing environmental testing.

In other areas of beautiful and cheap land, there are groundwater contamination zones in certain places due to chemicals used in the 70s and before on golf courses and nurseries.  

Usually they will have to cut out all the mold contaminated area, locate and seal the leak is. more than likely a roof replacement will have to happen.

Always keep in mind, of course, that such a letter applies only to what contamination was known about. 

Now that the end of the year is coming he is complaining about not passing his inspection for his permit (tattoo shop) due to the windows letting contamination in lol he’s been passing the last two years and I’ve never received any copy of inspection saying things needed to be fixed and he refuses to send me any.

I assume you mean "contaminated brownfield"My best understanding is:1) Banks won't fund it (prove me wrong someone?)

I understand that should I purchase this property, I would most likely be held liable should the debris remain and a storm wash it down the hill onto the neighboring property, contaminating their land.  

I've bought crap real estate before that was worth less than what I paid for it due to unrecorded city work liens, Govt restrictions, difficult title issues, past due taxes, and environmental contamination. 

Illustrates the importance of understanding prior uses of property. https://www.pnj.com/story/news/2019/10/11/santa-rosa-county-couple-finds-dump-new-property-near-gulf-breeze/3913016002/

another example of why need to do environmental due diligence for non-industrial properties. even farms can be contaminated. https://www.nj.com/ocean/2019/11/this-rural-nj-paradise-was-almost-destroyed-by-toxic-chemicals.html