C'mon, everyone has made this mistake. I was young--that's my excuse--when I paid money to watch Nelson:

The Big Pink. I was on the guest list as I knew the band who were supporting so I got in for pretty much nothing and they were dire.
Babyshambles. Pete Doherty was off his face on crack.
Well that was a shock wasn't it...
If festivals count Rizzle Kicks,Awful.I wasn't shocked though.