However, many people forget to recognize that an important part of running a business is Mindset and sweeping away all contaminants of the mind really helps to stay in the game in the long run.

Is it the risk of environmental cleanup liability if there's soil or groundwater contamination?

If that well made them sick ( which is very easy to do with contaminated water) having owned a Mobile home park on private water system myself.. you have a lot of liability here..  

Not sure what you win by telling them no they can't test except the appearance that you are hiding a meth contaminated house. 

Also check to see if the property is in a flood zone and whether there are any environmental contaminants.

Was there contamination?

If the first stage of investigation reveals existing or potential contamination, then a “Phase 2” and possibly a “Phase 3” are necessary to determine wither contamination exists or the extent of such contamination, along with remediation strategies.

You may be able to go with smaller lots since no worry about water well and sewer leach field contamination.  11.  

@Michael Knaus I'm straying a little here but that insulation in question is likely vermiculite - not the pipe insulation which is a different use of asbestos.https://www.epa.gov/asbestos/protect-your-family-asbestos-contaminated-vermiculite-insulation

My suspicion is, the dead guy won't bother to redeem the property.My main concern is environmental contamination.