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.

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. 

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

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.

I have met all the tenants in the house except for one lady because she just moved in last month.

Reflective metal type labels are also available.

About an inch of concrete behind the tile walls with metal lathe embedded into the concrete.

Washer knob is already broken and it sounds like metal on metal grinding during the agitation cycle. 

These are mechanical systems that use a master key (a real, physical key) and a tool (a pointy metal toothpick thing).

I purchased a 3family home in Philly (it already had a system I think) big red metal circle and fire alarms on all hallway floors.