Just to be clear, DCC is not just a scam imposed on Americans by merchants outside the USA; it is international and is spreading like a cancer metastasizing through the travelling world. American merchants pull the same scam with the same lies on visitors to our shores and their credit cards also charge foreign transaction fees on them. When all is said and done, you may be paying up to 8% if victimized by this scam or agreeing with the philosophy that it is a service and good to know the exact value of something in a currency you understand.

Nice summary of dcc above. Just one minor corrction. A foeign transaction fee is imposed by many banks at least in the USA for purchases processed by a processor outside the USA. Thus for example, if you buy Aer Lingus tickets from Orbitz over the internet in a transaction that never leaves the USA, you are still nicked for the foreign transacton fee as Orbitz transmit the charge to Aer Lingus which processes its mc and visa transaction through a processor in Ireland (no surprise there) which means bingo another 3% despite the fact it is a US based transactin all the way.

And just to be clear as noted above, if the merchant refuses to do a charge the proper way with one of the lies they have readilly available, do not offer to pay cash. That is just rewarding them for their illegal attempt to derraud you. Simply cross out the amount in your currency, write dcc refused and initial that. Or if the merchant refuses to accept the charge sans your signature, just cross out the statement agreeing to be scammed and when you get home, dispute the charge. As this is a clear violation of mc/visa procedures the charge should be charged back to the merchant although if it is a small amount the bank may simply absorb the difference which may seem trivial butit's the principle of the matter and the only way to combat this scam.

Finally when checking into a hotel and renting a car outside your naitive land, watch for the scam of them inserting a phrase into what you're signing agreeing to be scammed with dcc. This can be difficult especially when they write this in the local language but it's one of the ways merchants, even some big time merchants such as Avis and Mariot, two companies who I know have pulled these shenanigans, have tried to pull this off.

This thread should be very good to hear the experiences of people being scammed by this monstrosity to help us all learn what we can do to avoid it.