They're bots. They're on every server - if you look at their gear they always have white electrum gear to bind for materia equipped; usually of a different class to their actual class.

I don't understand why the GM's don't just swoop by that spot daily and blanket ban everyone there who so much as looks like a bot, because the bots have been there months; I gave up even trying to report them, being so many and the fact nobody ever does anything about it.