The true test. Do the players have real talent? Do the songs hold up without production tricks?

Who went acoustic and blew you away? And who failed the test?

Me:
BRMC - did a great acoustic set in LA couple mos back
Nirvana - of course, but funny their best tune (on MTV) was TMWSTW
Pearl Jam - saw 'em in SF a few years ago unplugged. Not my favorite, but their talent was undeniable.
Razorlight - to stir up some shit, really. Despite perrenial pishers here the acoustic Golden Touch I heard on the radio last week was very good.

I can't think of any failures just now. I just type this stuff and hit the send button.