As someone new to organizing a comp, and seeing it first hand for the first time...
Judges score differently. Some are more lenient than others, some are very sensitive/offended by certain off flavors. Others don't have the depth of vocabulary or experience to pinpoint what exactly is going on that is detracting from the beer but they know something is unusual. Moreover, it also will depend on when the judge gets that beer. Was it after the acetic oxidized gusher that completely ruined their palate? If so they may have missed the prominent diacetyl that was present and mistaken it for caramel (this was a true story, it went to mini BOS)
For another example there was a beer that on paper was almost perfect. body, aroma, flavor, mouthfeel were all within guidelines although on the outside of the style in certain areas. But it was boring as hell, in a flavorful style, was muddled, and none of the flavors were where they should have been. It got a mid 30s score, and I'm absolutely positive this will be the exact reaction when they get the scoresheet.