Well, here are the judging criteria for the traditional categories (fiddle, banjo, and traditional band) at Clifftop:
"Contestants in all traditional categories will be judged on rhythm/timing, tonal qualities, expression/soul, difficulty, and old-time style (20% each), with highest scores going to traditional old-time tunes/songs played in a traditional old-time style."
The third category, "expression/soul", was added by request of the judges some years ago, and seems conspicuously absent from the typical criteria I've seen listed for many contests, including suggestions on this thread. But what could be more important than that in a musical performance? Is not emotional expression the whole point of playing music? It seems an empty exercise to me without its inclusion.
As a Clifftop fiddle and traditional band judge myself three years ago, I heartily approve of the criteria that Bobby Taylor has set for the trad contests; they pretty much cover everything I care about in old-time playing. I guess I could add the musical interaction of the members of a band to the list, but to me, that's pretty much implied in the above criteria.