In the shows that I attend I am usually one of the best sellers, and other photographers seem to sell a little better than more traditional art forms. This is quite chaffing for oil painters, etc who sometimes allude that "cheap photography" somehow unfairly undercuts their sales, or at least that's the rationale they come up with for their own lagging sales. That's a pretty common feeling and when such a disgruntled person reaches the selection committee, you're doomed. But my basic attitude is...f**k 'em, there's always another show.
One thing's for sure, at least in my locality the best shows include photographers and they sell very well. Fortunately the art buying public has more liberal views on the relative merits of photography versus traditional than do some galleries and selection committees.