A lot of factors come into play as to why short sales do not work out and buyers move on that we could discuss for years to come.
The appraised price and the price the bank may want to selll house at are two different things.
The biggest thing is to exercise patient as you noted and due your due diligence.
By getting the facts, you may be able to come to your own good conclusion! A big issue here would be to determine why each of the previous sales didn't work out. Was it because of the seller, the buyers, the lender, or circumstances. You should be able to find out!