Don't know about the tradition of Irish prize dancing, but in Pennine clog dancing Lancs and Yorkshire, the judges sat under the stage. It didn't matter what someone looked like, what mattered was the tap of the clog on the boards.

As for the costumes, when I grew up it was nuns who taught the Irish dancing. Nobody would have DARED tarting up their daughters in front of Sister Raphael...
Quack!
GtD.