Dubai
Shops asked which currency to use but the option to punch is not uniform. Have seen at one shop option 1 represents AED, option 2 represents home currency and then the exact opposite sequence is found at the next shop.
Then at an Iraqui restaurant in the Al Rigga neighborhood, far from the tourist area but in the heart of the "local foreigners" area, I forgot to tell a waiter to use AED when he asked if I could pay cash. Nope, didn't have enough AED with me only had cards. I was distracted and forgot to emphasize to use AED. He came back with a "customer copy" that showed AED or USD but it did not even require a signature and was a done deal in USD.
The bill was below $50 - $47.xx to be exact - billed as $49.49. So the DCC is at 5%. I saw the pending was $47.xx in the correct translation but the actual posting was $49.49. Kind of strange because I have never seen a nonDCC pending then a DCCed posting.
Since the absolute amount is just $2.50 I am not going to dispute it even though I was never given an option.
At the Dubai Mall the US burger chain Five Guys just ran the card in AED without any option to choose.
In Hong Kong now. Had dim sum at Jade Garden at Star House by the Star Ferry. Again the waitress told me "HKD ONLY. We don't take Union Pay!"
Had a new pair of glasses made. The payment went straight to HKD.
So I gather that the DCC in Hong Kong largely confine at hotels and restaurants appeal to expats.