My sister and I went to a classical music concert in Vienna. I'd been to one a few years ago during my last visit, so I knew that the 20 Euro tickets didn't get you VIP seats in the State Opera - it was a small concert in a small room. You don't always get the best view past the (fellow) scruffy backpackers with hand-held video cmaeras, but you get to see classical music performed in Vienna, and that's what makes it fun.
The well-travelled Canadian family behind us didn't share that view - they had actually expected to be watching a 20-million-piece orchestra in the State Opera. When their little girl started giggling at Johann Strauss' "Wiener Blut" on the list, the father announced, "the chances of us being around for the wiener dance, are zero!" And they weren't ... their loss.