It's a good theory, but I think as a whole, Canadians just really suck at guessing accents. We can identify that someone isn't speaking like we do, but when it comes to guessing where they're from, we're basically clueless. It goes something like this:
Irish person: Excuse me, can you tell me where to find Niagra Falls?
Canadian: Hey, you're not from around here, eh?
Irish person: No, I'm just visiting
Canadian: You talk funny
Irish person: Um...
Canadian: You're Australian, arent ya?
Irish person: No actually, I'm from Ireland
Canadian: Oh okay, you've got a British accent then
Irish person: *highly insulted*
Canadian: Lets go watch hockey, eh?
Basically, if someone doesn't have a Canadian accent, they're either Australian, British, or from the United States.