The Osho Zen Tarot- it's not a tarot deck. It's weird, the instructions are cryptic and it does absolutely nothing for me. And since it's in Norwegian I can't even sell it.
Gendron- bought it for an average price, wish I hadn't. Didn't speak to me at all. Thank the Goddess for the "I don't love you anymore"-thread
Vampires Tarot of the Eternal Night- to me the cards look all the same. I love dark decks like the Bohemian Gothic and Deviant Moon and I also love vampires, but this feels flat and doesn't speak to me at all. For some odd reason I can't make myself part with it though, it's like it's begging me to give it a second chance.
Destiny Tarot- what an awful way to kickstart a budding interest in the tarot. This was my first deck and I still shudder at the thought. Thankfully it didn't put me off tarot for good, but it was a close shave.
There are several decks I'm not really using(Fenestra, Der-Jen and Lisa Hunt's Fairytale Tarot spring to mind), but I can't say I regret buying them.