@Brian Antonucci  yes, I walk through the unit before move out to give them a chance to remedy items before I withhold deposit. 

This includes fire or electrical hazards, plumbing issues that can result in a lack of hot water or water damage, lack of heat, lead paint remediation, etc.

Already capital for acquisition is drying up, now all that has to happen is accentuate the problem so there is a form of mass tenant rent defaults and as groundwork is in place for no remedy for landlords, thus a financial catastrophe situation.

If the vapor is coming from the soil, wouldn't the proper way to remedy the situation involve actual soil removal/clean up?

You want to avoid a lawsuit, and a demand letter shows you mean business but concurrently allows the seller an opportunity to remedy the problem before it escalates.  

The geologist and toxicologist hired by the plant for ground and air sampling has assured me that the property is not in the contaminated area (I have these contacts because my current residence a block over has vapors coming in through the foundation and remediation in progress). 

Obviously we will see how this plays out, but a lease is a legal contract and unilateral changes to a contract are not generally a judicial remedy. 

Hi Biggerpockets,“What remedies to expect/use on wholesalers that keep the ‘good faith escrow’ and don’t return it?”

Full scope rehab included new kitchen, 2 new bathrooms, new flooring throughout, all new windows, new exterior paint, and significant mold remediation as well as several serious deferred maintenance items.

Finished attic, unfinished basement, hardwood floors and steam heat... the images of all the rooms seam to be in good condition, nothing paint couldn't remedy.