It is not something you could have prevented or knew would happen and did not take measures to prevent it.again, consult a lawyer.

Not to say "success" is only measured by your income, but I learned a ton about the retail world: financing, due diligence, a bit of leasing and PM, etc because I worked for a retail operator.  

Since when investment success is measured by the level of leverage one uses to invest?

Very costly if you ignore a septic tank and don’t have preventive measures in place with your PM to clean them out 3 to 5 years. 

I'm not sure how to measure the upside on rent.

Always look for preventative measures that avoid catastrophe.

I have been warned about grease and grime in kitchens in apartments because of the traditional foods immigrants cook that require extreme cleaning measures during tenant turnovers with these people

In construction there's a saying "measure twice, cut once", it's good advice in a multitude of situations. 

Mismanagement of trust fund money is a big deal & licenses have been revoked, suspended or sanctioned when mismanagement is proven.

I learned the hard way that if you don't take measures like that, then if you do have to go to court a judge won't give you anything.