Aye. I’ve noticed activations with CEPT-style callsigns being spotted on 5MHz recently. When you’re operating in another country it’s important to make sure you know the local allocations, rules and restrictions. Wikipedia tries pretty hard, but there’s a lot more complication out there than one page can cover in detail, and with that much detail in one page it’s easy to miss things even if they are mentioned. Even when you find the other country’s rules they’re probably not short and sweet, and may be in a language you’re not crash-hot at reading. (I found a version of the German regulations in English. My German’s not good enough for me to be sure of the quality of the translation. I’ve not yet found an English version of the French regulations…)
See also Out of Band Operating on 60 Metres. It’s definitely yet another trap for the unwary. (… and see also Giving an extended try to 60 m tomorrow on HB/BL-013 for related discussion on picking frequencies.)