This is a more difficult subject than it looks. We should of course learn how to pronounce Spanish place names properly – I mean Toriaveka and Fwejiroller just won’t do at all, and neither will the miriad of local horrors such as Almoradí pronounced AlmorARdy; San Miguel pronounced San MigWELL; Quesada pronounced Coosarder and my personal favourite, Dos Mares pronounced like “two horses”.
However, sometimes there are established English pronunciations for cities – Barcelona, Seville, Corunna and Saragossa being among them. The problem is that you can sound like a real poser in English if you say “I’m going to Barcelona next week” -pronouncing Barcelona with your best Spanish accent.
That comment is not meant to be an excuse for bad pronunciation, but I think it all boils down to making yourself understood to whoever you’re talking to.