Don't you just hate it?

I'm all for bands advancing and not playing "greatest hits" sets every gig, but I really do not understand why some decide to barrage you with a load of songs you've never heard at gigs. It is almost impossible to take them in properly, as sounds/instruments are often drowned out in a live environment.

Example: Beck at Islington Academy decided to play Guero in it's entirety before it was out and it was the most disappointing gig I've ever been to.

I don't think it's "challenging" your audience to do something like that, I think it's silly. I'm not saying bands should never play new stuff live, but shouldn't there be a 2 song per gig limit or something?