Secret Squirrel was dealing with a fake ghost, 4 years before Scooby-Doo.
In "Captain Kidd's Not Kidding", Yellow Pinky (Paul Frees) poses as the ghost of Captain Kidd to steal an ancient Spanish galleon that was just raised from the depths by the Panaravian government. Mel Blanc resurrects his "Mexican guy" character from The Jack Benny Program in the form of a Panaravian representative, while Frees is also the news reporter conducting the interview, and, in a hint of the future, tossing in a sponsor plug for the "ghost"'s appearance. I don't know who wrote this story, but it was ahead of its time in a lot of respects.
Edit: 11/4/15: Unfortunately, the video has been deleted due to a copyright claim issued by WB.
Blanc & Frees had such good chemistry together. It's just a shame that the only other project the two did together was the movie, "The Man Called Flintstone", the very next year.