Perhaps I'll do a quick summary of DCC behaviour outside China:

Taiwan and Thailand: a quote slip is generated, the terminal pauses, you tell the cashier whether to press yes or no into the terminal. If yes a DCC slip with confirmation box gets generated. If not, a DCC-free slip gets generated.

Japan: DCC virtually unheard of, but recently started with full choice given.

UK and France: appears electronically on the POS system. Cashier makes input yes or no. Sometimes they forget to ask but the POS cannot void/refund in your currency (thus locking in the profits).

Korea: akin to UK/France. Except the slip's in Korean so sometimes difficult to figure out whether you've been DCCed (or whether you even got back the card slip!).

Italy/Spain - on signature pad if signature is captured there.

Vietnam: not seen...(?)

Indonesia: illegal due to central bank restrictions (card charges must be in IDR).

Cambodia: used my USD card (see below)

Sorry no info on Australia or the US cos I've AUD and USD-denominated cards and some savings in those currencies.