Originally Posted by
Pseudo Nim
The preauth is not the problem, the eventual payment is, since you might not realise it until you've left the hotel or whatnot. At least now with the preauth you can remember to flag this as a problem.
DCC conversion requires active cardholder consent, any slip you sign has to have the consent field in it to apply DCC, you also will notice a final bill being presented in another currency. If you didn't consent then you can dispute the DCC element of the transaction.
Difficult not to remember to pick up a bill presented in a third currency.