I found this to be abused in the past.  

And, just like buy/sell, it makes it a dual agency agreement that’s ripe for abuse.

It's their investment, the tenants are abusing them and will continue to live free unless they are forced to vacate.

I need some advice...I have a tenant who wants to terminate the contract after just a couple weeks living in the unit becuase her boyfriend became abusive and put her in the hospital... she has no job and can not pay rent... he is in jail and can not pay rent either...  

I am not concerned about everyday Joe looking for a place, I am concerned about the person who knows the system and is looking to abuse it.

And if you do it more than once, the IRS catches on pretty quick that you're just flipping and abusing the system (not that that's your intention, just that the IRS is on the lookout for that kind of thing). 

Contractor's take too much abuse from property owners.

Then tell them no.Many may think that is a A hole approach as a landlord but in reality you will ultimately regret ever saying yes, tenants simply take advantage of and abuse any privilege you allow them.

In that case they may simply have worn out, although I have never heard of knobs failing in that short of a time.If you can not conclusively determine it was tenant abuse there is really no way you can put the blame on the tenant.

We've used coin-op machines in the past, however depending on if you are renting A or C properties, there could be serious damage if tenants abuse the machines.