It's a sad truth nowadays. Top-level, good geared people forgetting, even not knowing some instances/zones exist.
In a few stories that happened to me:
I was in SW with the ZG sword, and a hunter asked where i got it. I told him ZG, and he asks, what's that? I say Zul'Gurub, and he asks, "Where is that?" I tell him, STV (Stranglethorn Vale) He then goes on asking WHERE IT IS. His first few guesses where: "Isn't that where the Night elves start out?","North of stormswinds?", ands my favorite: "OHHH! its that place where ragnaros is!" I immediately put him on ignore and cried for a few hours.
It's a shame older content is forgotten, or even not known be high end people, and how they reply like "lol l2life nub" if we know all this...
Anyways, my ranting is over, any comments/stories you would like to share?