Comment by kaybe

As a government you'd probably want some insane theories floating around so you can hide the less insane but real secrets inbetween - after all, conspiration theorists are rarely taken serious.

An example in the UFO case: You tested your new amazing stealth plane, but something went wrong and there are reports. However, if they fit the common UFO sighting tropes, chances are the whole issue is ignored/misinterpreted, leaving the secrets you want to stay hidden.