Receipts are one thing, but the tax thing really ticks me off at shows, you just know that in many cases they're pocketing the difference.
I went to a gun show with a friend who's a CPA and they pulled that on him from a 'guy selling stuff'but insisting on collecting sales tax. He broke out into terms that he later said you'd have to know if you had a business license and were indeed collecting sales tax to pass to the gov't. Total blank stare was all he got back. He told the guy, "Look, you can stop this nonsense about a sales tax you're not passing along. Either you drop that now or I report you for tax fraud. So, what's it gonna be?" Not knowing who he was dealing with (he had no idea of my friend was a cop or something), he said not to worry.
We reported the vendor to the gun show pewople on the way out anyway.
