4. Plug Back In, Please: Not everybody is well-suited to the Unplugged experience. Nu-metal gods Korn proved this conclusively with their 2006 performance. Robbed of the down-tuned fury of the band's signature slap-bass and seven-string crunch, singer Jonathan Davis' vocals sounded thin and dumb, particularly with insightful lyrics like "Life's gotta always be messin' with me." Mercifully, his trademark scat singing was mothballed for the show.

Tacked-on appearances by members of the Cure and Amy Lee of Evanescence only added to the frowns. Korn was not meant to unplug -- period. The group's off-putting performance was a nadir of the series, gladly forgotten by fans of Korn and Unplugged alike.

3. Y Kant Tori Continue? In 1996, Tori Amos seemed like an obvious choice for Unplugged. Often, it's just her up onstage with her piano, anyway, so why not just stick her in a studio with an audience and some candles? Slam dunk!

Well, not quite. Turns out the show was a little too intimate for the songstress. Tori told the awesome site WorstGig.com all about it:

What happened was I just couldn't harness the energy. And I got really mad at myself because I couldn't harness it. And I do this every night and I can usually harness something, and I couldn't understand why. What was wrong? What was I missing here? So I walked off (crying).

Talk about emo. It looked like the show was over. Luckily, Amos said, her anxiety had a simple fix: Lowering the lights.

All the lights were up to catch the audience and I felt like somebody was watching me take a shower. So they dimmed the lights, I felt better. By that point because I'd made the choice to stop it and make some changes, I felt like I began again. And I turned the whole show around.