Since MMORPGs are a rather huge part of what I localize, I am always flabbergasted when I hear colleagues telling me that they never played one. I do not mean the kind of translators who do not play video games at all, I am talking about all those condescending Halo geeks and asocial Fallout 3 players. No offense
Why not try one, for free even? Most companies offer some kind of trial version. Restrictions are usually time and level limits, but even as a level 10 Night Elf Mohawk you get a pretty good impression of what it means to play an MMORPG.
Here is a list of games with free trials: