This isn't a marching band/DCI judge and isn't about negative feedback as much as confusing judges. This year I was in a "We the People" competition in Arizona, somewhat similar to speech and debate except it focuses on the constitution and is formatted like a senate hearing. After my group was done presenting, and the judges had asked a few questions, the head judge stopped the time 50 seconds early and said "okay, we're done, that was amazing, and we don't need to hear anything else." There wasn't a single negative comment from the judges, it was all about how we were the best thing they'd seen all day. Well, after losing the overall competition, we got to see the scores of my group compared to everyone else who was there. The school right before us beat us by 3 points out of 180, despite everything they had said about us. We really wanted to know how they beat us, especially after being called "flawless."
Of course, that has nothing to do with drum corps judging. Just one of the weirder things i've seen judges do.
And with any event with human judges, there's a lot of room for human error. It happens, so one just has to get used to it in this sort of activity/any other one that ranks based upon judging.