I visited my first hoarder house today that reeked of rodents, mold, and fumigation residue.

At the time when the chemical industry discovered farmers as a huge market all sorts of herbicides and pesticides (the are banned today) were introduced, stored and disposed of basically into the ground: the farmer did not want to have stuff growing between the barn and the farmhouse anyway, so seemed like a good spot to kick that barrel over.

I will say, with furnished rentals, it takes time and money to fully furnish them with all the bells and whistles but it did allow me to get higher rents... only downside is, if you are out of state, it is not easy to manage remote unless you have a good property manager/company.I have personally started to transition out of STRs due to zoning/town regulations and have already unfurnished one of the apartments to turn it into a long rental for more stable residual income.

And the moment someone discovers toxic chemicals in the ground on a property you own the value will plummet b/c no one will want it. 

I know in New Jersey, you cannot bill if you clean it yourself outside of the actual chemicals used (I.E. free labor).  

Try these options before busting out the heavy duty chemicals.

We agree with @Travis BiziorekBay City, Saginaw & Flint all have low price points, but little to no growth.There are better opportunities in Detroit, even Midland (home of Dow Chemical).

Then buy the proper chemical to spray on that will take research to figure the proper type  .

As an investor, the goal is to generate consistent residual income.

My housekeeper drains my hot tub after each guest and replenishes it with water and chemical that they provide.