Never accept rate of conversion when traveling to Europe and paying with credit card
I know this has been discussed before, but I want to emphasize the scam that foreign travelers face when paying by credit card in Europe. Always choose to pay in euros and REJECT the offered currency conversion. If you accept the conversion, you are effectively choosing to pay in USD and accepting the exchange rate set by the merchant’s payment processor, which will be significantly worse than the rate your credit card network would otherwise use (more than 20 percent), often with an additional “convenience” markup of 5–10%.
And somehow this is allowed to continue. You have to remember that Europe/EU is run by an army of bureaucrats who seem incapable of addressing things like this, while one of their most visible achievements of the last 15 years is making sure you can no longer remove the cap from a plastic bottle.