EVERYTHING is up to each judge. I've seen things DQed that shouldn't be, and things that were not DQed that should. Generally when exhibitors are upset with a judge at a show, it isn't just about one breed, it is about a number of breeds or classes.
You can protest, but it has t be done pretty rapidly, and you have to put up money (returned if found in your favour). It is rare to see it happen.
I think judges are getting pickier about wings. Before the APA National in Shawnee in December 2010 (self-blue qualifying meet) I had never seen wings marked down on cards before--but dang if it wasn't marked on a HUGE number of cards there. And looking at the wings, there were a fair number with problems. Probably not as many as were marked, though.
At the Silkie National in 2005(?) in L.A., every single buff was DQed for having black in wings and/or tail. Mind you these were all mostly clear birds. None had more than a little bit of black.