At the end of the day the buyers decided to settle out of court for about 1/2 the remediation cost vs going to court and potentially getting nothing. 

Yeah call the insurance company and pay a big deductible to fix a 200$ door and buy a used Craigslist stove .that would be bad for two reasons - a high deductible that is probably more than what it would take to remedy the situation and the fact your insurance rates will spike up .

Thats a serious issue and you should contact an environmental remediation company.

Professional remediation by a disaster cleanup company.  

The headache of dealing with this situation and the possible bed bug remedy costs (they were told $2,500) was enough to scare them out of the vacation rental business.So you never know, as some have mentioned above, check with the selling agent and see if you can get more details.  

Fortunately, many of those have been remediated but there are still a few hanging around.

We, too, were alarmed when discovering that Maryland is chock full of natural springs, so I can totally imagine the buyer walking, but they likely would have walked anyway unless the seller could prove exactly what was causing the water problem and that whatever remedy you used completely solved it with a long-term full warranty to back it up (and likely not even then).  

When we acquire a building with asbestos, we usually price the cost of any remediation into our offer and deal with any potential exposure before placing the building for rent.  

You want to stay away from any use like gas stations, auto repair, dry cleaners, etc. that would require environmental remediation.

Clean-up and remediation can be extremely expensive and may require ground water monitoring (annually or quarterly) for years.