Lately this discussion is coming up again and again in my community, the question is which expert is more valuable for us? There are four major groups during these discussions;
1- Experts to be very careful about, they are exactly matching the Question Authority definition. Also very unfortunately some of their sites always come at top when you do an Oracle topic google search, they may have some internal relations with google search engine I believe and I hope someday google may be able to give the most accurate information at top :)
Also we are lucky that the experts in the coming third category are very motivated to argue these guys postings with facts, numbers of course.
2- Experts that do not add value, they just continue to duplicate the documentation with some other examples or stories of experiences. These guys are very useful for a newbie since newbies are after the easiest way around the documentation usually. Some of experts in this category are internal Oracle employees so they do not force their capacity to share the internals deeply, just some good examples and useful contributions.
3- Experts that really add value, they put a lot of effort in research. For years their books stands like pyramids, you still will be reading these unique stuff after 11g even it is written 8i on the cover. Usually they have never been related to the company Oracle, but they love the core business of this company-the database software called Oracle :)
They are the reason after 10 years reading you still believe you are just started and have to work harder.
4- Experts that we may never learn their names, these guys have been writing the kernel that we are very in love with and they are totally internal and anonymous unfortunately :)