Same was asked upon checkout at Marriott SkyCity Hong Kong Airport.
The lady at the counter asked what my preference was for the final charge: a currency conversion direct to USD or no conversion Hong Kong Dollars. I asked to be charged in HK Dollars and she checked as such. On the bill given back to me, a typed 'X' was present on the HKD.
This isn't a surprise to me though, buying Duty-Free in International Airports for example, I'm always prompted by the cashier to either pay local currency or do the direct conversion. Just be careful.