Someone in Lisbon said this to me: "We get a lot of Spanish tourists. We smile nicely and take their money. Then we have a laugh because they've no idea how much we hate them." The last time I heard something like that was in Jordan after they opened the border to Israelis – only the Jordanians left out the smiling nicely bit.
We "hate" tourists for a whole lot of reasons. Perhaps they symbolise the big and noisy neighbours. Or maybe they represent an unpalatable culture or religion. Or sometimes tourists are disliked simply because, like those Spanish in Portugal, they're oblivious to what we really think. Remember that scandal in the Maldives where two local wits did a scurrilous commentary on an English couple's video of their wedding in paradise?
The people in Lisbon and Petra weren't bitter and twisted. They were hospitable, intelligent souls who didn't appear to have a misanthropic bone in their bodies. But then hating tourists, or certain tourists, is the sin that does dare to speak its name – it's something that normally nice people will happily admit to.
All of which brings me to London, the Olympic city. Otherwise pleasant Londoners regularly deprecate tourists. Why? For what I can make out, it's nothing more than the sin of getting in the way.
Really, this is a failure of empathy. When we go about our daily business in our home cities, we are like bats flitting between each other at pace – and just as blind to our surroundings. When we are travelling, we dawdle, look up, gaze at interesting locals. Of course we get in the way.
I'm not pretending to be blameless. I work on the Strand in central London, and at 5.30pm at Charing Cross station, I'm more like an ice hockey player barging aside the idiots trying to negotiate the barriers with their useless maps and plastic policeman hats.
US visitors bring out the very worst in us. Most Americans, it seems, approach travel in a spirit of big-hearted innocence and friendly curiosity. Just because they exhibit those traits in loud and confident voices, some Londoners take a dislike to them.
Why? The dollars they bring are vital to our economy and, just as important, our status in the world. We should be going out of our way to thank them personally for coming over, especially those brave ones who defy the US's regular fits of national collywobbles when there's a bomb within 1,000 miles of the UK. Those people should have a personal welcome from Boris Johnson and a special map advising them how to avoid the Aberdeen Steak House.
I asked someone senior in the British tourism industry what she'd like to change about our image abroad. She said: "We are admired rather than loved ... they don't see us as fun-loving and some are unsure of their welcome."
One nation, she said, had very successfully turned around its dour reputation. They're now seen as almost hedonistic and certainly tourist-friendly. The Germans.
If that's not a call to arms, I don't know what is.
Mark Jones is editorial director of British Airways' "High Life" and Best Western's "Do Not Disturb' magazines