Template:Dead Horse Trope
A Trope which has gone way beyond being a Discredited Trope to where the very act of parodying and/or subverting that trope has itself become a trope.
The progression is generally:
Clever idea → Trope → Discredited Trope → Dead Horse Trope. → Then, if the downward slide continues, it may end up as a Forgotten Trope.
Named for "Beating a Dead Horse" - an old idiom that describes continuing to do something pointless long after it would be obvious to anybody not mentally handicapped/under the influence of the Sunk Cost Fallacy that said course of action will yield no results and is simply a waste of time.