And at the same time tell them you're going to be painting the building in a few days they need to be out of there by Wednesday - or something like that . 

Even if it is paint, flooring, some new appliances, and some yard improvements.  

On one of their finds, they told us that they found black mold in the kitchen and bathroom, which is interesting since I painted and redid the faucets in those two areas, and saw none.  

I’ve seen landlords successfully sued for large amounts due to refusing to remove dead trees resulting in injury; not complying with swimming pool enclosure laws; having window frames in such bad condition that window ac units fell out; refusing to disclose existence of toxic mold; not eradicating lead paint; and many more.  

And I had put so much work into their apartment, new carpet, painted, fixtures and on.

Paint it, remove green weeds and green window cover thing, maybe black top the driveways.

I’ve owned a dozen properties for almost 25 years and I’ve spent less than $500 on roofing, and zero on exterior siding/painting.

If it's an old wood window that can't be replaced or blocked super easily, you could always go down to the studs from the inside, put a piece of treated plywood (painted black) over the window itself, and screw that into place so that it's flush with the studs.  

Oh, do you think you can paint the walls before I move in?

This house only needed a full paint job, hot water heater and new flooring.