Lots of opportunities to stop and prevent it. 

Reason being for it is that insurance companies are getting tighter and tighter, and having a claim on your home can prevent you from getting further policies in the future and subject to much higher rates. 

Owner preventative maintenance.

It is your responsibility to change the air filter to prevent this from occurring (see Lease, page 3, paragraph 2). 

Who was I to stand in their way and try to prevent them leaving or enforce the terms of the lease?

Forming an LLC in a specific state believing you will be better protected is not true and will not prevent claims from arising.Understand insurance and make sure you have the appropriate types of insurance depending on the investment opportunity you are pursuing whether it be land, a construction project, a tenant occupied property etc..

Seller is free to tell his broker to limit inquiries to qualified (screened) buyers, as I mentioned above -- you assume that buyer with their own agents are qualified (pre-screened), but that doesn't prevent you from screening a buyer without a broker and IF he qualifies, have his sign a no agency agreement.So no, there is no "all/random" persons of inquiry.

If there are potential consequences that will prevent her from making $ off of the other agents/assoc. brokers, she'll sign.All the best!

@Olivier Colson You will first want to find out if the locality has any “Just cause” regulations that prevent you from non renewal, or any other provisions that may keep a section 8 tenant in place.

.), but larger ticket items that may require multiple bids, permits, or otherwise could have reasonably been prevented should be handled separately and charged to the owner.