Each rabbit has a Standard of Perfection. Within this Standard, are the "rules" for how each breed is supposed to look. On the show tables, the judge is judging based on how each rabbit of that breed attains to their Standard. The rabbit that has the most points, the rabbit that looks most like the one described in the Standard, gets the highest placing in the class. Mind you, there are no 100 point rabbits out there. Every breeder will tell you that. Some of them have come darn close, but as of yet, the "perfect rabbit" just doesn't exist. Yet we're all striving for it. Winning isn't as important as it may seem. Ribbons and legs are nothing if you aren't breeding purposefully to "better the breed", or to breed strictly to the Standard.
In reality, depending on the situation, it can be fairly easy to win a ribbon or leg. Even with a lot of rabbits in the class, depending on their overall type. If there are five rabbits in the class, but all of them have major faults, like a shoulder dip, weak ankles, low head mount, etc, yet one has a fault that isn't considered major, but still severe, then that rabbit will win, depending on the other traits. But that doesn't mean that it was actually a good quality, or that it deserved that winning. Because all the rabbits were lacking, one of them had to win, and that doesn't mean it's a "great" rabbit. It just means it was, in the judge's opinion, not as faulty as the others.
Two different judges can also have entirely different opinions of a rabbit. So you can get Best of Breed in the first show, and then 3/5 in the next show, even up against the exact same rabbits. It's all relative to the judge's interpretation of how the breed is described in the Standard. Not all judges raise the breed you do, and not all judges have studied that breed thoroughly enough.
How can you know if your rabbit, the one that placed BOB and then only 3/5, is good or not? And which judge can you fully believe?
Go to a trusted breeder. Get his or her opinion of your rabbit. Ask how they would place him in that same class. Talk to the judge. Ask how long they have been judging, how long they have raised rabbits, what breed they raise. If one judge raises my breed and the other doesn't, I'll know which judge is more likely to have placed my rabbit truer to its quality.
As breeders, we should strive to "better the breed". We should strive to produce that 100 point rabbit. Each of us has a unique outtake on life, and a unique perspective of the interpretation of the Standard. Not everyone will feel the same way about the same rabbit.
Keep in mind, that the MOST IMPORTANT thing, as breeders, is to ENJOY WHAT WE DO. Don't raise rabbits if you hate them. Don't go to shows if they drive you up the wall. Successful breeders and exhibitors are those that truly, truly enjoy what they do. Raising rabbits, breeding them and showing them, brings us joy. Maybe not all the time, like when we lose a baby or a homegrown junior decides to knock a tooth out, but in the long run, they make us happy.