So many factors can affect a parcel's value including topography, soil quality, zoning, history, utility access, road access, shape, etc.

Well, at first glance it appears to be human excrement, BUT the bowl on top of the tank indicates that a person has "created" a mess by filling the toilet and mounding it up with soil from the backyard, which explains the bowl used to transport it into the house.  

Because good supplies dry up.  

Also, ask the neighbors (if there is any) about the soil.

I mean you can't just up and move your farm, the well you dug, the soil you improved, etc...

I Highly recommend asking if he has any soils reports, surveys and any engineering reports for the property.

The point is, no one in 2008-2010 would buy these portfolios anymore so by Mark to Market accounting these 1 trillion dollar portfolio derivative securities were worth nothing or pennies on the dollar even though they were still generating a massive return regardless of how many foreclosures were going on.This plus so many practices are not happening anymore so even though the rates might go up, money might dry up, and the real estate market might take a downturn or level off, there will not be the cataclysmic fall out that you saw in 2008. 

The lower level is dry but shows indications of mold on the floor, walls, and ceiling throughout.  

Add non-porous soil.5.

Usually within a few minutes the sun will come out and dry everything off.