There are many, many things that can happen to prevent a closing even after getting a clearance to close, especially in this day and age. It is for this reason that some purchaser's attorneys want it written into the contract that if the bank refuses to lend anytime prior to the closing that the purchaser would be entitled to get back their down payment.
A mortgage contingency in a contract would be satisfied once the actual commitment was received. Thus if the bank refused to lend after the fact, the purchaser would risk losing their down payment. There have been so many changes in the way mortgages are underwritten these days that certain buyers who would have been able to get a mortgage several years ago have a tough time today.
If the buyer are supremely qualified, you really do not have to worry too much, unless they use a bank who suddenly goes out of business, but that would be a fluke. You state that the buyer "has been put through the ringer", I think that most of the time when that happens is because there was something lacking in the buyers qualifications to begin with. That in turn would mean that either a) someone didn't do their homework properly when qualifying the buyer or b) the bank made a mistake when they told them they were qualified in the first place.
I will say that 99.9% of the time when the buyer gets clearance to close they do close. So if your buyer got clearance to close you should be crossing that finish line soon. If I can be of further assistance, please contact me direct. Good luck!
Mitchell S. Feldman
Associate Broker/ Director of Sales
Madison Estates & Properties, Inc.
Office: (718) 645-1665/ Cell: (917) 805-0783