I honestly don't know what my dealer specifically does, but there's always been a little time on the three I've boughten (one that was ordered). I know he drives them into the shop to hook up mowers, FELs and such, then drives them out to his lot to put in the lineup and if you want to test drive one he'll let you...
I don't think anything major would really show up until the tractor was actually used and not just ran on a dyno or driven around the lot. Murphy's law if you will.
I do know that even if you test drive the one you are going to buy that he brings it back into the shop to go over it and put a coat of wax on it.