Oh dear, can nothing be simple:

http://www.guardian.co.uk/money/2007...oreigncurrency

Since other banks are monitoring it's acceptance I suggest that we all boycott it as much as possible. If they see we don't like it maybe the other banks will actualy listen to us and not introduce it. Faint hope I know but worth a try.

Talk about muddying the waters! This article says that it is not always a better deal to accept the choice of one's home country's currency (which the article describes as choosing to use your own bank's exchange rate) and suggests that it is sometimes better to take the DCC option and pay in the local currency.

It does sound from the article as though there are more fees for people using UK banks abroad than there are for me when I use my US bank card, which incurs no currency conversion fees (except possibly the 1% VISA fee. I say possibly because when I work it out I do not find that 1%, and the rate appears identical to my Capital One credit card rate, which purports to have no conversion fee) and no percentage or flat rate transaction fee per use.

So, if you have a debit card that does not charge for *any* ATM and assesses the 1%Visa foreign trans fee, then DCC will never ever be the better choice. That should simplify it. (Compass Bank)

Or even if the debit card home bank charges $1.50-$1.75 per withdrawal but 0% foreign trans fee, that's better than DCC as well. (Capital One)

I have come across this in August at a Spanish bank ATM (can't remember if it was Santander). But the choice was very clearly displayed, in English, whether to accept the cash withdrawal charge in euro or in sterling (my card's billing currency), with the resultant sterling amount highlighted.
So I'm not unduly concerned about DCC - you just have to be vigilant and read any message that's displayed before you hit the proceed key.
Other ATMs may of course not be as clear in showing the options you have.