In order to see form the betta must flare. When they remove the cards from between the bettas the fish are expected to flare at one another. If they don't flare full form can't be seen and they can't really judge it, and it's an expected part of betta personality that that flare aggressively. As you look at the bettas you are allowed to remove the cards so you can look at the form (many of the bettas are up for auction after the show, so it's important to get a good look at the fish) and I noticed that none of the fish that didn't enthusiastically flare, regardless of how amazing they looked, placed at all.
SIP Spitfire, Dyson, and Spike