Forget trying to sue an individual....there are a lot of hoops to jump through, and Evidence to provide, to make that stick.

Some valuable anecdotal and fact based evidence you've provided.Your email to the author really clears things up.

I would not walk into a court-room with the "they breached their lease" argument without strong evidence of their continued/uncured breach...When you say "filed the eviction" do you mean you served the tenant a Pay or Quit, filed the Forcible Entry and Detainer motion with the court, or have been granted the FED motion and have now filed the Writ of Removal?

Depending on your state's requirements, I usually will buy decapitated ugly homes directly from the public with no agent involved and in those situations I have a disclosure that states specifically that the seller is selling the home significantly below market value (I also wrote the the ARV in there so theres no evidence that the seller or buyer didn't know what they were buying/selling).

So, I sent someone to inspect the property and I can't find evidence of such.

Look for win-win where possible.Police removal of trespassers, if necessary, can often be accomplished far more swiftly than an eviction, but may still require substantial verifiable evidence of ownership (e.g., legal deed, etc.) and absence of a lease (e.g., shown in affidavit/statement from former owner-dad). 

I would imagine that someone who lived in one of those properties showed evidence of lead poisoning. 

While this evidence is anecdotal, there have been many reports about developers moving inventory to recoup cash.

So when you have a post like this, where accusations are made, based on anecdotal evidence, that can tarnish someone's reputation and, therefore, their livelyhood, keeping it up is counterproductive to what this forum is about.

Use that evidence to demonstrate the value to the tenant and justify your increase.I would not sign more than a one-year lease.