That's a tough one. The problem is that bad games are usually very cheap, so there's not a lot lost if you get even a tiny bit of enjoyment out of it.
The only one I can think of right now is the Burial at Sea expansion to Bioshock Infinite, which took a messy but enjoyable story and made it messier and less enjoyable. I thought the story was dumb and confusing when it ended the first time...
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