I am still surprised by the "I have never seen this thing (I couldn't possibly have observed by happenstance) therefore it must not exist" argument been thrown around.

Unless you vacation 10 times a year and love to snoop into other tourist conversations, you are very unlikely to have witness much. Ask people in the service industry and they will tell you.

Also, no I am not saying people traveling to Greece should learn Greek... but they should definitely expect to repeat themselves a bit, maybe use simpler language and definitely not expect perfect American English spoken back to them. This is what I was referring to which is likely represented by a loud MINORITY of Americans that give everyone a bad name.