My 'rents saw the Moody Blues in the early 90s in GSO, NC and loved it. I was 9 at the time and didn't like anything but metal or rap. Now I love the Moody Blue's Music.
At the time, i really liked the Moody Blues music too, but sometimes the show doesn't live up to the music. And like with The Who it was the other way around.
My husband always HATED Tom Petty's music. He'd mock him by singing in a nasally voice. But this time i dragged him kicking in screaming to the concert. He loved it and since then he loves Petty's music.
Oh, and another major disappointment, was a very recent Bob Dylan concert. He sounded baaaad. And normally i like his sound. And he never addressed the crowd with a hello. He said Thanks once maybe twice max. And i don't recall him even saying goodbye at the end. And to top it off, no encore and "Like a Rolling Stone" sucked!