Lately I've been borrowing some music dvds from my local library. To sum it up the listening experience was quite disappointing. Out of the 10 or so I could only find one where the sound was on par with a studio recording or even better (it was from Dream Theater). Together with the different camera views which were cut in a good manner this particular dvd was a real pleasure to watch

In the other mixes people growled or applauded over the music and the balance between different instruments / vocals was quite off.
The same goes for live recordings on media without accompanying picture material. On a music dvd the visual show makes up for an eventual lack of sound experience but I don't see much arguments in favour of a live cd.
What is the reason for you to listen to live music?