On a previous trip to Tunisia, I was slightly surprised to discover that many tourist-focused vendors (though not all) offered two prices, one in Euros and one in Dinar, with the Euro price quite a lot better than the official exchange rate would've worked out as. Annoyingly, I hadn't known this in advance, so hadn't brought any euro notes with me. (I suspect that currency exchange restrictions had something to do with it, as I've had a similar experience with EUR and USD pricing in Sri Lanka which also has restrictions)
Reading the money section of the UK FCO advice for Morocco, I see that the Moroccan Dirham (MAD) is non-convertible. That lead me to wonder if the same thing might apply there too.
So, at touristy places in Morocco, is there typically any financial advantage for paying with Euros rather than Moroccan Dirhams? (i.e. should I pack some euro notes, or just my no-overseas-fee card with which to withdraw dirhams)