Sorry to hear that your transaction didn't go through, but If the attorney missed a contingency, I don't see how it can be the sellers fault. It is VERY IMPORTANT to go over the contracts with the attorney whether you are the buyer or the seller. Not only that, but good communication between all parties is key. I had a homeowner look over their contracts before they were sent out to the buyer's attorney and there was a correction that needed to be made.
Once there is an accepted offer, it is usually contingent upon the home inspection. I have never been involved with a home being in full contract and the home inspection was done afterwards. Maybe each state is different.
My warning to buyers and sellers would be to make sure the Attorney is a Real Estate Attorney that is familiar with the Township you are purchasing the home in, that you read over the contracts before signing them and to make sure that if there are any contingencies, they are written in the contract.
The Realtor(s) involved with the transaction should have open communication with the Attorneys unless their is a unique circumstance.