Potential home buyer in your park doesn't pass background/credit check

When a potential mobile home buyer fails your park’s background/credit check criteria, how do you go about informing the mobile home seller—and just how much do you tell them? I realize that there are stringent privacy rules, but how does the seller know whether the park owner has a legitmate concern or is just yanking the seller’s chain?. Is there some official document that declares a buyer has been refused and for what reason?