Answer:
The most important thing you need to know about the judge is their qualifications on that subject.
Lets say its a Trivia contest. The judge needs to have a history with that subject that the trivia will be on. You wouldn't want them giving the wrong answers.
Another qualification is that the judge should not have a biased opinion.
Lets say its a modeling contest. If the judge fancies a certain contestant that wouldn't be fair to the others. Same as if the judge hates on of the contestants.
You need to make sure the judge knows the rules and has a good history with pointing out mistakes or flaws or whatever the contest needs them to look out for.
While its not required, its best that the person you want as the judge has an interest in that subject they will be judging.
Judges need to be focused, have a critical eye, good evaluations, able to give constructive feedback, and good decision making qualities.
They have to be committed to this job. If the judge doesn't have a spark for what's on the table, the outcome will be bland.
Your judge will also need teamwork qualities. If they cannot work well with other people, they may not be the right fit.
They need to know the right questions to ask the contestants no matter what the contest is.
Like if its for a baking contest, "why did you choose to make this cake rather than cookies"
I believe that should be enough criteria for your question.
If you need further assistance don't be afraid to reach out. I hope this helps!
