Movie 'Cliche' or classic plot point?

One of the "IBDB reviewers" of the 1939 "Bob Hope" comedy/mystery version of THE CAT AND THE CANARY questions what he perceives as a "cliche" treatment of the solution (as added/elaborated on for this version of the oft' filmed play. Without wanting to give away the solution (the perpetrator disguised as/passing for a presumptively trustworthy other character), I wonder at the characterization of this classic element (it can accurately be said to date back at least to ancient Greek drama with the essence of King Oedipus) as a modern "film cliche."

While Hope cracks jokes about dramatic elements around him ("breaking the fourth wall" to either comment to the audience or as interior monologue to expose thoughts is still a recognized comedic and even dramatic tool, and doubly effective when someone with an easy going, effective modern comedic style like Hope uses it), the specific character masquerade used in this 1939 film was picked up by Agatha Christie in an original mystery play of her own in the early 1950's that is still running over 50 years later in London's West End!

Cliche or classic plot element? It would be interesting to see some serious research and film or play lists as to the earliest uses of this specific *character's* use to disguise a miscreant (murderer or thief) - at least in the era of "talking film."