This may seem harsh judging by several folks comments on here but I think it is really the most compassionate path.

Transients may seem like a harsh description of renters/vacationers but it is what it is. 

@Chris Harjes,Mel's response is a bit harsh, but he's not wrong, either.

For that, it has to be chemically treated to kill the mold.

When operating off of imperfect information, as one always does, assumptions have to be reasonable.Inexperience and ignorance (harsh word, but many in business ignore readily available news) are challenges. 

I believe that's a bit harsh; after all, mankind has yet to sample and observe any actual population of scum growing on this planet to behave so wicked as to somehow deserve such an insult.

Generally a Phase 1 EA/EvA/ESA is concerned with contaminates to the underlaying land - {abandoned} Underground Storage Tanks (USTs); past uses of the premises or property which may have involved (petro)chemical, biological waste (i.e. abattoir) or hazardous materials (i.e.

Ask what their steps are what chemicals they will be using.

I don't think that people were even all that harsh at first.  

I once flipped a house that had a long term smoker and we literally had to wash the walls down with a chemical.