Vote with your wallet. If the dealer doesn't sell anything, the dealer doesn't come back to the show after a while. Generally the Nazi-saturated tables up in NY are guys who got started when their uncle or father brought back a buncha bayonets, walking-out bayonets, and uniform pins, and the hobby snowballed to the point they buy and sell.
Gunshows for a newbie have one VERY IMPORTANT cardinal rule. Don't buy anything you don't know about. Gunshows are more about exposure to guns you'd never heard of than buying anything- you have no idea what a good price is yet, or if it's a good gun.
Go see what you like, look it up, learn about it, and the next show you can consider buying it.
Also, gunshows are uniquely fun because you can literally strike up a conversation with anybody and have a pleasant discourse on a mutually enjoyed topic. Everybody's friendly at a gunshow, it's like Christmas for grownups!