My point is people are forgetting that the game has fantasy elements and is not supposed to be a real-world simulator. Gold can be a entire race of termite people for all I care. I was pointing out the ridiculous nature of the question OP was asking.
Look at http://en.wikipedia.org/wiki/Suspension_of_disbelief.
Backward flying dragons breaks this.
Mines "restocking" does not because it is a game. Were it real life, you could dig deeper or start a new mine.
Were it real life a dragon flying in any direction would be questionable, not just flying backward.
The OP was a legitimate question, your rebuttal was not.