I've only been to 1 gun show (last spring) and I wasn't there intending to buy a gun (although I was tempted a couple of times).Part or your confusion comes from what is being reported in the media vs what is actually the law. There is no gun show loophole. Any dealer selling at a gun show has to do a background check the same as if he was selling at his store.
That said, my impression was that if I had wanted a gun I could have bought one. I didn't see any evidence that background checks were being conducted. And I did see several people buy guns, a majority of which were cash transactions. NTTAWWT. Did I just miss the background checks because I didn't know what I was looking for?