Planet Payment is the acquirer at the Hong Kong SkyCity Marriott. According to what the receptionist said he charged me as a preauth, their markup is now 5.35%. I just checked my post from a year ago and it was 4.4%. Now, I never saw the receipt this time, so I can't tell for certain. However, I will be able to confirm within a week what the markup is. As I remember, I hadn't seen anything north of 5% a year ago.

Things with DCC have gone from a 'reasonable' - and I use this term loosely - ~ 3% markup (sometimes under 3%) 10 years ago to more than 5% today. In the case of US cards, there were few 0-1% cards back then, so at the time it might have been advantageous to accept DCC if the fee were under 3% and your card had a currency exchange fee. You didn't get rewards on the exchange fees, so if you wanted to use your hotel affinity card it would make sense to bill in USD to maximize the rewards.

However, most issuers stateside switched to foreign transaction fees. The transaction occurs in USD? Doesn't matter. You still get hit with the 3% fee. (Many of us have been stung by this by booking tickets through the website of a foreign airline. Things would price in USD natively, and no currency conversion happened. However, the transaction would post with a 3% FTF.) After the change to FTF, DCC ceased to be a good deal in pretty much every possible circumstance. The only exception is perhaps someone on an expense account reconciling exchange rates. However, most businesses I know go by the interbank rate with perhaps a little leeway in favor of the employee, and you'd have trouble passing off an unnecessary 5%+ extra expense. There have been stories on here of people being on the hook for €50 after willingly accepting DCC.

When does this cross over and become extortion? If you're getting a 5.45% DCC + 3% FTF, you're bound to notice the discrepancy with your billing statement. When do you say enough is enough? If it becomes harder to dodge the scam like in Mainland China or India, it might incentivize people to pay using cash or cash cards. (Many times in Taiwan or HK I use my EasyCard or Octopus, respectively.) Why waste the time arguing a DCC battle for some spending that might total $100 in a week? Even with a 2x category bonus, that's 200 miles or points which amounts to $4 of rewards in the most generous of valuations. In these cases, even if you dispute the difference, the issuer will not begin a chargeback and likely issue a courtesy credit. The result is that the merchant and acquirer are never punished for non-compliant behavior.

Personally, I've already modified my behavior in DCC rampant locations with non-universal compliance like in Hong Kong. I use an Octopus card (funded with cash from a 0% FTF debit card) for all small purchases for which I would use a credit card back home or in a place where DCC is uncommon (Australia or Canada). This is the opposite of what Visa and MasterCard want, but I'm left with little recourse as I want to save my principled fight for those cases that will actually affect positive change by forcing a currency code chargeback: hotels, department stores, and restaurant bills where the discrepancy amounts to something where the issuer will not simply issue a courtesy credit.