I've never made a credit card purchase in Africa, so I can't explain there. I only did a day trip from Algeciras, but my guess is that DCC wouldn't be prevalent in a place like Morocco. I wasn't willing to find out at the carpet shop though!

I can only speak for Taiwan, HK, and Macau DCC experiences in Asia. Taiwan is very compliant - after a period of being extremely non-compliant. It also helps traveling with a native speaker. On my most recent trip to HK, I was able to opt out of DCC successfully at every place but Greyhound Cafe when I was with percysmith. Some restaurants in HK and Macau don't respect DCC choices, and you have to be wary when you get the carbon copy paper with the check box. You need to make sure that the cashier can input something to disable DCC after you've seen the verbiage.

DCC, at least as of June, was still uncommon in Australia. In my seven trips there in the last three years I have only seen DCC twice, both times in Brisbane. The first was at Coffee and Chocolate at Queens Plaza in Brisbane (unexpected) and the second was at F1RST Tax & Duty Free at BNE (expected). In the first case the girl had handed me the terminal to enter my PIN (even though I was using a US chip-and-signature card), and I saw the prompt, "USD 23.7X OK?" The cashier was monitoring and said, "Just press ok?" when we both stared at the prompt. I don't think she had ever dealt with a non-AUD card before, and her confused look indicated she wasn't trying to get me to accept DCC. I used the opportunity as a brief educational moment. "Sometimes the banks offer an opportunity for unsuspecting tourists to pay in the home currency, but it's a rip-off exchange rate. It's just another opportunity for these banks like ANZ to make money." Oh? ANZ is pulling the scam? Now we have a common nemesis. Heh heh heh... In fairness, I saw a bunch of other ANZ terminals in use that did not employ DCC, so I don't think the DCC cancer is widespread. There was another case of an eatery in Strathfield, but this is extremely rare. I've generally found the service in Australia to be friendly and accommodating. Known DCC culprits like David Jones and Myer can easily be avoided by specifying upfront that there will be an option, and you want to decline the option and pay in AUD.