Plus, they'll blow all the top soil away, too.  

The wall is to the living room, and this is a split level so underneath the living room is the lower living level or mechanical room, I think.

If the stairs had rot underneath and there was no visible damage by the naked eye, then is that negligence? 

And yeah the soil here can be tenuious.

I have an Oreck Carpet scrubber that does a decent job on normal amounts of soil, and we rely on a local carpet cleaning company for anything beyond that, so either way we've got more time or money wrapped into clean carpets than we would in clean hard surface floors.So far, we haven't removed carpet and found wood floors worth finishing, but if we did that is the route I would take. 

Wait til someone puts a soiled dog bed in your washer, it's out of order untill it's cleaned out and the next customer will be ticked!

I noticed most of the ones in need of some TLC are charging much lower rents.The one surprise I had was a busted cooper waterline that runs underneath (or within) the slab.

NO bad soil like some states from Texas through Mississippi. decent landlord laws. 

We now need to get soil reports done, a structural engineer involved, etc. so we can firm up the plans.

With any lock together flooring you want a fairly consistent floor underneath the installation.