If you've ever lived somewhere where a lot of tourists visit, then you know how annoying they can be when they don't respect your local customs and habits. Travel and Leisure talked to people from 14 different countries and asked them what the most annoying thing tourists do when visiting.
One Italian, for example, complained that "Foreigners are pretty convinced that Italy is a lovely land without laws [...] and they think they can do everything they want. Well, let me tell you a tiny little thing: YOU CAN'T. You can't have a bath in the Trevi Fountain. You can't pee in the streets in the middle of the night. You can't climb the several statues that adorn our historic centres (they were made by Bernini, Canova or Michelangelo you fools, have some respect for our geniuses!)."
A common complaint by people across the globe is about travelers who treat the local poor like tourist attractions to be photographed and gawked at. You can read the rest of the comments over at Travel and Leisure.