I am also going to hire a professional mold company to come in and test what is left after you tried to eradicate it.

A healthy diet of realistic expectations, patience and some work should pay off more times than not.

They can tear up flooring, scratch holes walls (once had a less-than-wise tenant keep his dog shut in a room - the dog scratched multiple holes in our drywall, as well as obliterated both the bedroom door and closet doors), and urinate on the floor (if it gets into the subfloor, its nearly impossible to eradicate).   

You can charge a fee or higher rent but it does not change the fact that you risk having to redo floors, eradicate urin smell, replace molding and door frames etc.

Daily exercise, proper diet, getting enough sleep, and quiet time. 

@Jeremy MangenRoaches are difficult to eradicate.  

Even the smaller German ones can be eradicated in a few trips across a couple of weeks.  

Setting up marketing systems and doing the work is the diet and exercise protocol though in a world full of binge dieters. 

Sometimes, even a more complicated C-corp is the best choice, and sometimes just a plain LLC.It's like keto enthusiasts eat a high-fat diet and praise its supposed health benefits.

I do not have the capital to upgrade the existing electrical and plumbing, but can put on a new roof and eradicate all the pests (roaches and rats).