As much as I enjoy all the Poirot episodes, I have to make a negative comment on this one. It is impossible that waitresses who served the artist on a regular basis could mistake the costumed nephew for his uncle. Standing two feet from someone they'd seen week in and week out, surely they would notice a wig, false facial hair and the fact that this man was decades younger than the one he impersonated. They'd already said he ordered completed different food and came in on a different day; it's highly unlikely they would ever have mistaken this pathetic caricature for the real man. It's so far-fetched as to be ridiculous, and I doubt if anyone, whether they knew the old man or not, would look at the counterfeit and not see through it.