Actually this scam originated in Ireland and has since metastasized through the travelling world.

Yes, the scam originated in Ireland in the mid-90s and was created by Brian McCarthy of FEXCO.

Interesting tale:
When I was at Budget car rental desk at Dublin Airport a couple of weeks ago, I needed to prepay for the full tank of fuel, around 90 euro. As I handed the card, I asked specifically to be charged in euro, and it was done. The amount came to about £66 when it hit my card account (my card has no foreign usage charge ). When I returned the car with the tank full, they reimbursed the same euro amount, but they DCCed it and gave me the amount in sterling. It was around £69. So I actually made a profit of about £3 by playing at their game!

analogue: >>Accompanying friends with foreign cards, I have heard the question about DCC asked maybe 2 or 3 times in France in 10 years. Nobody has ever told me that it was imposed on them.<<

Very possible -- but the vast majority of travelers have no idea what "DCC" is or even to be concerned about it. Many if not most visitors think the merchant is doing them a favor by charging them in their own currency. Fodorites are a small sample size of (mostly) very informed travelers -- but the typical 'civilian' has no idea they should be on the look out for DCC . . .

Just paid for dinner in (chilly and very damp) San Sebastian. As the waitress picked up my CC, I said, "in euros, please". She smiled knowingly, and said "I see you came prepared".

If machines are set to default to DCC, and if the merchant is not required to ask verbally prior to the transaction, then the CC companies should require at the least a clear "opt in or out" choice (in the language of the CC issuer) that must be made prior to the transaction's completion.

I'll apologize here for not spelling out in my original post that DCC = Dynamic Currency Conversion. As pointed out above, many travelers are not familiar with this fairly recent development. For more information:

https://en.wikipedia.org/wiki/Dynami...ncy_conversion