Hmm, not wanting to enter the fray lightly, I'm going to nominate the manitou HT frame for consideration. Never had one, never ridden one (though I have seen one hanging forlornly in a bike shop, displaying its design flaws to all who cared to look), but the tales on here of cracks and dents appearing after staring too hard at the frame make me think that this frame design pushed the limits of the tubing a little too far, making them almost unfit for their intended purpose of riding. In my view then, I think the frame fits the topic.
I'm going to duck now to avoid the missiles being hurled my way.