@Joseph Caracappa  he started with a little Gestentner printing press were you had to put metal dies that wrapped around the drum then.. feed it paper and ink..

While a metallic footprint consistent with a large metallic object present, the absence of a fill pipe or vent pipe necessitates the need to excavate the area with shovels.

However, they left some rust stains in the corner of the bathtub (what looks like from a metal can they had there), I've tried CLR, Lime away, bleach, etc. and I cannot get this to come out. 

Even if I met all those standards, I will be discouraged to rent it because I may think somewhere between the lines, I don't qualify.

Any metal etching primer? 

One turnover, the electric coils in the heat pump set up wasn't working, but that wasn't because of the cold, it was just an inconvenient time.

Met all of the tenants when I was first looking at the place with my realtor and they seemed like they'd be tenants that I'd want to keep.

For example, a metal door, I will use a semi-gloss oil based paint.

Also, they pay for damages or dirty coils if they fail to do so. 

They are a fairly cheap to build metal building with minimal land costs meaning they can easily jump locations and from what I have seen they have absolutely no problem with moving over one lot and rebuilding at the end of the lease.