I'd be curious to know if they identified the source (i.e. the original spill(s)) or if that was cleaned up and these are just the residual contaminants.  

Once they’re clean you really only need a light scuff to promote adhesion of primer.

if there is residual contamination below the slab, it could pose a risk of vapor intrusion that could prevent you from renting the property for residential.

Came out well but that residue needs a lot of cleaning.

Once you renovate everything, there will be residual damage done when the foundation work is complete post-renovation.

I would have probably kept my property management company with over 200 SF homes for the residual income. 

You will need stuff with good residual effect.Good luck and be glad it's not bedbugs!

I told them that they should collect the rents that are due on the 1st and prorate the rents for the first couple days and deposit the residual rent into an escrow account...They want me to collect the rents but I don't think this is a great idea... 

I've seen the floating vinyl plank flooring work well, but I was wondering if the self-adhesive LVT which costs half as much works holds up just as well.

yes anything that produces residue that sticks to the wallS can cause issues.