Landlord Reference Issue -- Is This Common?

[Jeff Carroll]

I had a very good potential tenant family for one of my properties apply today, and I ended up losing them to something I never would have thought of.  Their current landlord convinced them to stay after he got my reference call!

The family had been told that their current landlord was going to sell the house they were in once their lease was up on 8/31.  The owner of that house had given them the option to stay on month-to-month until the house sold, but they decided to look at other properties so that they wouldn't be forced to move with little warning once the house sold.

They viewed (and loved) one of my properties, and put in an application.  They were excited about my property, and all of their information checked out.  My final step was to speak to their current landlord for a reference.  He gave a glowing reference for the family, and wished me well in my business.  Next thing I know, the potential tenant, who just an hour earlier was ready to sign a lease, calls and says that they would be staying in their current house.  The owner had decided not to sell since they wouldn't stay on month-to-month until the house sold, and he convinced them to sign a new lease with him!

I certainly don't blame the potential tenant.  I understand not wanting to move if you don't have to.  My question is whether or not this is a common issue (the previous landlord convincing their tenant to stay after they get a reference call from a potential new landlord).  If this is a common issue, how do you avoid this?