As stated already, it truly is a relative question. There are 2 kinds of experts in my book. First, there is the over-hyped, star studded group that publish articles and are glamorized by the major fishing rags and newspapers. I've run across many of these "experts" over the years in my own travels and, in many cases, found some to have no exceptional knowledge or secrets........some of them even snag!
Then, there are the real experts. In my opinion, being a true expert seldom extends beyond a fisher's local geographic area. These are the folks who concentrate on 1 region or river, share info. with people they trust and think the biggest sin on earth would be to write articles broadcasting their mastery or locations to the world. Exploring and putting in the hours on your own get these guys' respect. These same experts also cringe when a local fishery is printed in a magazine that may be a delicate, fragile fishery because they know the catastrophic effects it can have on that fishery. At the same time, they breath a personal sigh of relief because they know they had no part in "broadcasting" the news.
I've learned more from this group over the years than any other. I think we all know folks like this in every area of the state, wherever we live. They put in the hours, develope an intricate knowledge of their river/region, don't have loose lips and quietly go about the business of kicking some butt on the water.