Now on my third re-reading of this worthy and highly underrated tome:
All opinions are not equal. Some are a very great deal more robust, sophisticated, and well-supported in logic and argument than others.
The Salmon of Doubt: Hitchhiking the Galaxy One Last Time. Douglas Adams. ISBN 0-330-41843-2, p. 98
My next quest will be to try to locate a copy of The Experts Speak (Christopher Cerf and Victor Navasky) as recommended by the sadly missed Douglas.