Common bleach solution does well,  50/50 mop the floor, let stand several hours and then rinse with clear water (you said you didn't care re the finish). 

I treated the sheetrock with bleach, applied mold resistant paint and then color matched the paint.

@Max James I actually like properties with mold issues, because they can get you a discount on the price... but I say that with the caveat that I firmly believe in proper mold remediation, and NO shortcuts (such washing things down with bleach, or painting over problems).

Then spray any affected area with hydrogen peroxide or bleach.

I like to use one gallon of concentrated bleach with two gallons of water and a cup of TSP.

Dehumidifiers, bleach, and hydrogen peroxide, along with removing any porous materials will solve just about any mold issue.

Some protective gear and some bleach with water and a good air purifier you'll be good.

It was actually pretty simple.I don't know about your specific situation, but sometimes it is as simple as opening up the space, and some bleach & water.  

Your SOL my friend, Brit has a good point there keep them in the unit smoke damage only really goes so far.Keep them long term and then bleach and paint all the walls when they leave install some new flooring if you have any carpet.Next time it's for rent the best way to determine a smoker, Ask to see the inside of the car they drive or their finger tips:-).

Something you might try with the black mark is bleach and water.