Originally Posted by Neverfly

ETA: Most government secrets would sound rather uninteresting to the general public. That's what makes them easier to keep. The main concern is not about a conspiracy in keeping secrets- just in not letting another government know.
An example is the shape and design of a submarine propellor. Big Huge Secret. Running silent is crucial to a sub and they don't want other guys knowing how we do it.
Not very fascinating to Joe Schmoe walking down the street though.