Bad card ideas? How about bad expansion ideas. Here's a preview of "Day of the Duchy":
Deku
Victory - $5
Worth 1 Victory Point per Duchy in the supply.
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When you gain this, gain a Curse.
Dooku
Action - $5
+1 Action
You may discard a Duchy. If you don't, gain an Estate. Otherwise, +$3, +1 Buy. Every other player who doesn't reveals the top 3 cards of his deck, trashes one of them costing from $3 to $6, and discards the rest.
Manager
Action - $6
While this is in play, if you buy a victory card, set it aside. Return it to your deck at the end of the game.
Redesign
Action - $5
+1 Action
Name a card. Reveal cards from the top of your deck until you reveal a Victory card that is not the named card. Discard the other cards. Trash the Victory card and gain a Duchy.
edit: Added price of Redesign.