Just returned from a trip to CN, JP and HK. Only saw DCC at hotels, but a stern 'I want to pa in CNY/JPY/HKD please' didn't start the spiel in the first place and the agents made the right selections on the POS. Nearly got hit by DCC at the HK Airport express.

Re big box retailers: in Germany grocery stores don't have DCC, but Galleria Kaufhof, a large department store chain will always offer to DCC you. The EUR option is easy to select though and not hidden.