It highly depends on the country. The worst offenders universally seem to be department stores and duty free shops. International hotel chains commonly impose DCC in certain geographies but not in others. In places where DCC has spread like the plague (Mainland China), expect to find it at every corner. I've heard through others it's nearly as bad in Ireland and Poland.

Some hotels in the UK (Marriott) will DCC you and claim there is no way around it. I have never used anything but an AmEx in the UK for hotels, so I haven't encountered DCC. It will also happen at upscale department stores such as Harrods, but you can specify pound sterling in advance and avoid DCC. Back in late 2011 I remember charging a bunch of things on a Chase Visa and not seeing any DCC charges. I charged at: SIM card vending machine at LHR, Heathrow Express, Kensington Palace, Wagamama Tower of London, London Eye, Sainsbury's, Tower of London, Hiba Express, St Paul's Cathedral, McDonald's, and Harrods at LHR x 2. That trip we stayed at the Grosvenor House on points, so I wasn't able to test DCC at a Marriott property.

In February my wife, a friend, and I were in Barcelona, and he got hit with DCC at a souvenir shop near Parc Güell. Hotel Arts made mention of DCC on its receipt but I watched what I was signing at check-in as well as upon departure like a hawk and made sure that the bill was in euros instead of USD. El Corte Inglés also supposedly uses DCC, but they can disable it if you ask them to want to pay in euros. I didn't buy anything from ECI this trip, so no data points there.

In March 2013 I spent about 30 days in a combination of Germany, Austria, Slovakia, and the Czech Republic. I made many purchases at restaurants and hotels, and I was only unwillingly hit with DCC at the Frankfurt Marriott. I sent a complaint to the general manager who more than made up for it with a equivalent amount of Marriott Rewards points. ^ I've heard that Starwood properties in Germany are also notorious for DCC, but I only stayed at the Sheraton at FRA and paid in a combination of euros and my AmEx. (I don't like using my Chase Marriott card at Starwood properties. )

In the seven trips to Australia over the last four years I've only seen DCC at a coffee shop in a mall in Brisbane and at the duty free store at the Brisbane airport. This is across multiple hotels, restaurants, fast food chains, supermarkets, convenience stores, tickets for tourist attractions, etc.

In Taiwan, HK, and Macau DCC is relatively common, but in most cases it's easy to avoid. I was unwillingly hit with DCC at the Venetian Macau, but I was able to opt out of DCC elsewhere. In Taiwan you'll usually see DCC at hotels and department stores, but they will always give you an option. In HK and Macau you need to specify more proactively or you will get ripped off. I've heard Singapore and Thailand mirror the experience in Taiwan, but I have yet to visit either country. I didn't see any signs of DCC in Japan, but I have few data points as it's mostly a cash economy.

I have not yet visited Ireland, Poland, or Mainland China, but these seem to be the worst offenders. In Ireland and Poland even small purchases like Burger King or cafes will hit you with DCC. Since the purchase amount is so small, you'll fall victim to DCC without even being able to deface a receipt or say "local option not offered". China is by far the worst with lots of non-compliant POS terminals and DCC at every turn.