Here's what's needed to prove a case of negligence:The Four Basic Elements of Negligence Presence of a Duty of Care.

People can look years older than their age due to smoking and other poor environmental situations.

Matthew, it is up to you, but outside of the ethical element of being an aboveboard landlord, Fairfax County refers to their zoning enforcement officials as the "Strike Team".

If you think it will last another 5 years replacing the element, repair it.  

If I had a tenant pounding crack in my place I'd make sure they went to jail, that can be a clean up issue as an environmental hazard.

Not to mention the high maintenance element Rachel, Sergio and Marcia pointed out.

Knowing ARV, estimating repair costs, etc. will make you a good wholesaler.Your focus should be on learning the business of real estate investing, as all the separate elements really are connected.

If the court continues get more forceful: "Your Honor, I have proved every element of my case for nonpayment of rent.

However; Modern style and Mid Century Modern both have many of the same elements including clean, simple, straightforward design. 

I am stumped.Now, I am going to replace the stove because of the issue with an element not working.