Big changes in soil moisture will absolutely cause movement.That said, I love buying properties with foundation issues; it limits the buyer pool drastically.Caveat, if the property has cast iron drain pipe, make sure you add into the contract that the house must be able to pass a hydrostatic test (a good idea even if there was no prior foundation repairs).  

I very nearly soiled my pants.

I know in some ag applications developers need to remove a ton of top soil that has bad stuff in it.. not sure about turf stuff..

The funniest story I ever heard was a family of small people rented a house out, paid rent on time every month for 3 years then they suddenly stopped paying one month and the owner went to check it out... why this guy didn't do an interior inspection yearly, I'm not sure...They had divided his vaulted ceiling house into two floors and built another floor for themselves and another family lived underneath them. 

Also am i in the wrong if i was to purchase this house from underneath the wholesaler who's clearly taken advantage of an elderly  person.

Unless the house is fairly new, it has likely done all the moving it is going to do unless it is seasonal due to expansive soil that is common in Colorado. 

My tenant put up a tent with a couch underneath and was letting people live/sleep there.  

Mounds are common in soils that dont perk well nowadays.

Things that affect value here:  crop type, water-well or district, type of irrigation, utilities, tons per acre, water rights or shares, dwellings or homes, soil class (1, 2, 3, etc), mineral rights. 

My two condoes and two underneath (1st floor) did not have water.