Random Observations - Opening Bands

So what is it with opening acts at concerts? Sometimes they can be quite good - I own Ben Harper, The Greenhornes and Filter CDs because I saw them open for someone else, and they rocked! But mostly, opening acts seem to be the bad stuff you have to sit through to prove that you're worthy of being up front in a general admission concert. Does the headliner choose a weak opening act so that they seem better in comparison? Here are some that stand out in my mind. Northern State (3 white chicks rapping badly) opened for Cake last time we saw them. John McCrea scolded the audience afterward for dissing the girls. Bright Eyes (gawd, they were depressing) opened the Vote for Change show in Philly. Fortunately, with the number of acts playing that night, no one was on stage for all that long. However, the worst had to be Children's Hour, who opened for Billy Corgan's defunct band Zwan.
I remember noticing before the show started that Zwan's equipment on the sides of the stage was covered in black tarps and the stage had a harp in the middle, and not much else. Hmm, that's odd. So someone comes out and introduces Children's Hour as "Billy Corgan's favorite band." Gee, with an intro like that, they must rock, right? Sadly, no. They were a singer/songwriter folk/rock act - the harp, a guitar, and other assorted folksy kinda instruments. If they were in a nice small venue playing to an appreciative audience, I'm sure they would be a good act to see. However, the wispy sound drifting around in the Electric Factory was just painful. By the 2nd or 3rd song people started shouting "you suck!" By the 5th or 6th song, people started throwing stuff (OK, that explains the tarps). They soldiered on to finish their set, but it was really just getting it over with. They got off the stage to everyone's relief, Zwan's crew came out and set up, and then a miffed Billy Corgan came out and got on with the show, which was awesome! It a shame that Zwan didn't last, cause they seriously rocked the Electric Factory that night.
So here's an open note to artists and concert promoters: I know you'd like to showcase talented young bands, and perhaps help promote friends. However, we learned a long time ago that even when the opening act is actually good, like say Jimi Hendrix, you still can't reasonably expect a crowd with different tastes, like say fans of The Monkees, to warm up to something that just isn't their taste. And when the band sucks, well, they just suck. Just saying.