The main point of this episode seems to be showing how pathetic and easily deceived Italians are. The biggest culprit being obviously Inspector Ravini. Not only he doesn't bother to get a photo of an allegedly missing person (Ripley), but he goes to Ripley's house, doesn't recognise him thanks to a ridiculous wig and moustaches and - worst of all - tells Ripley all details about an ongoing investigation.
Those are abysmally low investigative standards. Since when the police is at liberty to discuss a case with a person of interest? Not only that but Italian newspapers and magazines publish articles about Ripley and Greenleaf without a single photo of either... again, how believable is that? A big feature appears on a weekly magazine without a portrait of the missing guy when Marge could have provided tons? Yes, Italian are stupid and duped by smart Americans.
Being Italian myself I should be insulted, but I just found this last episode dragging on and being kind of OTT stupid. Even if Highsmith novel was good, sometimes a plot works only on paper but not so much when confronted with real details.