If you have classes of entry such as kit, semi kit, scratch, and also divided by boat/ship type, then you do need a judge/judges who can tell the diference between one and the other, also they should know enough about the subject to reach a technically correct answer. When you get to he point where several models appear to be equal, you have to start looking at small defects - nit-picking because it is necessary to put them in order, and docking points is the only way then.
However, a "Best in Show", if is decided by a random guest, will let the rest of us know what the public, or that member of the public likes about ship/boat models. Sometimes it is the biggest and shiniest, sometimes it will reflect superb craftsmanship, but it will always have eye-appeal. Sometimes it will really be the best in the building - sometimes they will pick the best decorative lamp-holder.
No names, but a fellow member of my club once bought a model that had gained a third in exact scale. My lady wife commented that "Its a hideous looking thing". The only answer is that the original that it was modelled off was also a hideous lookin craft, so an exct scale model would follow suit. In another (smaller) show it may well have been the best built, most exact model with the best construction craftsman hip imaginable, but the prizes would invariably go to anything else with eye-appeal, such as a semi-scale semi kit lifeboat.