There are lots of things that the good dancer does that are seemingly unknown or totally unimaginable to many twirl and barf dancers.
Good dancers fit their movement to the phrase of the music.
Most contra dancers dance at one speed and are thus often guilty of finishing a figure too early. The beginners did fine, the experienced contra dancers didn't listen. Good dancers embellish appropriately. I'll bet many people who think of themselves as good dancers couldn't get through a dance without all the extra twirls. They don't know what the basic movement is or what it feels like.