Data point: I was imposed with DCC, without my consent, at the White Hart Inn in Winchcombe, UK, at a rate of £1=$1.62, compared to the credit card's standard rate of about $1.57. I only noticed it after the trip. This was the only case of consentlessly imposed DCC out of about 20 credit card transactions in the UK. I've written to the merchant that it was not acceptable to impose DCC without my consent.