Then there's your HVAC ductwork that's been contaminated, circulating that crap. 

Was there any issues maybe with oil contamination?

Yes, it's not the use temperature, it's the very real risk of bacteriological contamination that can make someone very sick, especially if you have decent sized gaps between guests.

The gist is certain properties are deemed contaminated by the EPA (or an environmental report) and the government has programs that will clean them up for you as a way to prevent the sites from sitting unused.

These people honestly dont care about you and you shouldn't let what they say contaminate your business reasoning.

I'd probably want to do some air quality testing to determine present levels of contaminants, if any.That said though, the official guidance in the linked report remains to follow the CPSC remediation standards.  

Thanks to everyone for the great info - would you say a Phase 1 ESA isn't always crucial, especially when purchasing vacant land that has little to no chance of contamination?

What's done is done, but imagine this (since you already did research), what if the asbestos during your demo, flew and landed on your clothing, you bring them home, hug the kids, get them to inhale it, when you remove them and put them on the hamper, it contaminates it.

and great source for bed bug contamination for tenants is the RENTAL VAN they used for moving.

That's not the way I want to learn about dry cleaners, perc contamination and become friends or enemies with the EPA.I've seen the same with a couple of old gas stations/convenience stores.....want to be responsible for EPA gas tank leaks?