CAN you imagine?
I read somewhere that the accent David Suchet used for Poirot wasn't pure Belgian, but a hybrid of Belgian and French. The actor made this choice knowing that the pure accent would sound unconvincing to the casual listener. I can't really explain this, but have an example of my own. The daughter of an exiled Russian princess came to watch my Madame Galina show and said that my accent was accurate to the point of indicating social strata and where precisely Galina lived in Moscow. Other members of the audience thought that the accent had travelled from Cardiff via Crete to Bavaria and back again.
When Hercule Ease, part-time male stripper, performed his squaddie themed act in Chelmsford, he was advised to get a much more realistic looking soldier's outfit. Hercule is in reality Corporal Bailey, 9th SQ, and he had performed the act wearing his army issue uniform.