Ideally, one should make a Genius Bar appointment and then inspect the replacement before leaving the store.
Sounds like the OP tries to do this over the phone though. Whether that was by choice or not is the question.
In my case, the apple store is 60 miles away - they made an appointment for me, agreed to replace it when I was there, then realized that they did not have any in stock so I had to mail it in anyway.