Shocked, I tell you
An Italian consumer organisation has threatened legal action against businesses in Venice, where it's been revealed (gasp!) that cafes and restaurants maintain a three-faced price list: one price for Italians, one for tourists and one for "rude" tourists. The difference between the lowest and highest price noted is about 100 percent, but I'm sure the cielo is the limito if a tourist should turn out to be particularly rude, by wearing a Union Jack painted across his bare beer-belly, for example. Or by pronouncing the word Eye-talian. I dare say other nationalities could be similarly targeted, but surely not as routinely.
Read orl abaht it here, where you'll also find a handy guide to useful phrases in Venetian dialect. I would give anything, including four quid for a glass of cola, to see Telegraph readers trying those out.
Quite by chance, I also happened today upon this article on Miss Manners, her new Venice book, and rude tourists. However I should warn you that the only interesting thing about it is the coincidence.