I know what you mean Rich. It's happened to me before too. I have played in my high school talent show for the last 2 years (won both times! woo!). The first year I played, my band played a Primus song, and if you're farmiliar with Primus, you know that the bass is usually the focal instrument. Well...apparently the guy running the PA didn't know that the bass was supposed to make sounds, because I wasn't being heard by my bandmates, let alone by the audience. It was bad. Luckily though, the school didn't have the funds to hire a sound tech this past year, so we took it upon ourselves to set our sound system up. Much better. Lol.
I have a feeling that we'll be doing Whipping Post without an organ though. It may sound ok, but I will be surprised if it sounds GOOD.