DCC is obviously a scam but in my particular case it was especially blatant. I used my UK-issued debit card for a purchase in Dublin (Euro) and even though my bank (Citi) lets me link the card to the local currency (GBP/EUR/USD) to avoid the exchange rates and the 2.7% fee, the restaurant in IRL was quick to offer me a choice of 21 EUR or 20 GBP (!!!) as a balance even though the card WAS linked to the EUR account. Imagine anyone uninformed thinking paying in GBP is a better deal.