It depends on what you mean by experience, and I also think it depends on the thing somewhat. For example, I think you can be a successful movie critic without having ever made a movie, or even been involved in the movie business--but not without a lot of experience watching movies. If your are simply judging something based on its output--like art--then I don't think you need any experience beyond an awareness of other things of a like nature, so as to be able to make an educated and well reasoned comparison. With something where judgment is based on the elements that go into the creation of a thing, however, I do think you need to have a deeper understanding and more practical experience to judge properly. I also think if you are judging something with the goal of helping the creator to improve it, you definitely need a great deal of experience so as to be able to easily understand and explain the weak points and strengths in such a manner that the person you are judging can glean some useful feedback.