Not all judges are honestly qualified to judge a competition. Plus not everyone is good at giving feedback, and differences in opinion can produce contrary feedback.
I was a preliminary judge at the home wine makers competition at the NY State Fair for several years in the 90's. The judges were mostly home wine makers and mostly members of various chapters of the American Wine Society, so presumably all had experience in wine judging. We were given guidelines for judging. One was that we could not give a wine a low score because of sulfite smell. One year, the guy sitting next to me hated sulfite, so he ignored the rules and nuked (lowballed) the score on every wine where he could get even a whiff of sulfite. That was not cool. AFAIK, he was not asked back the following year.
Plus some folks can't judge wines they don't like, e.g., dry wine drinker judging semi-sweet wines. Or the reverse. Or white vs. red, or ...
Duration of the judging is another factor. Each year I tasted ~70 wines during a 3 or 4 hour period. Sniff, taste, & spit. Sample half a cracker to clear the palate and ready myself for the next sample. With a few exceptions, it was a lot of fun although I overdid my yearly allotment for crackers.
During the tasting, the folks at my table set aside the half dozen really good bottles, as we intended to have a glass after the judging was over. At that time I realized 2 things:
1) I was lit (lightly drunk). Even without swallowing wine, I got enough in me after tasting 70 wines to affect me. I didn't realize it until I stood up at the end. [Yes, it was amusing, and no, I was not the only one affected.]
2) When I actually had a half glass of wine, I couldn't enjoy it. My taste buds were badly overwhelmed. This made me wonder how fair I was to the last dozen or so wines. Until I stopped judging, I felt fine. It was when I tried to enjoy a glass that I realized the situation.
It was good that I was riding with family, as driving was not a good idea ... plus we wandered around the Fair for another 3 hours, which sobered me up. My tastebuds took a week to recover.
It was a good experience, overall most of the wines were at least "good". On the flip side, I recall a wine I didn't taste. I sniffed a wine, nearly gagged, and there was NO way I was putting that in my mouth. Not sure I'd chance damaging my sink with it. That wine produced the longest discussion, as we couldn't figure out what the maker did wrong. It made a badly oxidized wine smell good.