Gun show sales are absolutely NO DIFFERENT than any other sales, anywhere. If you go to Vance's to buy a gun, they're going to run an NCIS background check on you. If you go to the Vance's booth at a gun show; guess what? They're gonna run an NCIS background check on you.
Where people start getting pissy is the private sector of it. I can sell any of my own personal guns to anybody I choose, and I'm not obligated to run a check on them. This carrys over to gun shows. If I were to take my collection to a gun show, sit in the parking lot, and sell them to anyone that walks by, I'm well within my rights. People do this because if they're looking to sell or buy something gun related, then a gunshow is the place to do it. The Anti's have got it confused. They think that all gunshow sales are w/o a BG check, and that's simply not true.
Some people argue that a background check should be required of all firearms transfers. While this idea sounds good at first, it's really just another 'feel good' law. It goes back to the whole, 'criminals don't obey laws' argument. If they want one, they'll get one, and ultimately the only person you're making it harder for is the common stand-up firearms owner. I'm also one of the people who believes it's none of the government's fucking business who I do business with.