. §§ 90.396, 90.40324 hoursViolence or threats of violence by tenant or a guest; intentionally causing substantial property damage; giving false information on an application within the past year regarding a criminal conviction (landlord must terminate within 30 days of discovering the falsity); committing any act “outrageous in the extreme” (see statute); intentionally or recklessly injuring someone (or placing them in fear of imminent danger) because of the tenant’s perception of the person’s race, color, religion, national origin, or sexual orientation; second failure to remove a pet that has caused substantial damage

As far as "legal" goes, most likely you will not find the direct answer in your state's general statutes.

Statute of limitations has past?

Depending on local statutes, if you accept payment before they sign the new agreement, you just renewed their oral agreement.

The employing broker is responsible for maintaining all trust accounts and all transaction records, and the employing broker is responsible for exercising authority, direction and control over the Broker’s conformance to statutes and Commission rules (Rules E-29 and E- 30).

Landlord-tenant relations in Wisconsin are regulated by Chapter 704, Wisconsin Statutes, and by Chapter ATCP 134, Wis.

Definition of abandonment in PA:https://casetext.com/statute/pennsylvania-statutes/statutes-...

I'm sure there's no law/statute Requiring a mortgagee getting a property back at foreclosure to pay the past bills themselves.  

Wait out the statute of limitations on the mortgage debt. 

If you read the FL statute 475.01 you'll find that if you advertise a property on behalf of someone else and you don't have equitable ownership (title to the property) then you're brokering.