Let's face it, knowing what you're talking about isn't really a prerequisite for working in game retail.
I'm sure there are plenty of informed employees who do their job well, but there's also some real jokers.
There was this guy at my local EB who would always try and steer people towards the 360 version of multiplats, especially in my case as I was usually buying them for Wii. I can understand him suggesting the 360 version of Rayman Origins, but it got pretty funny when he tried to tell me to buy No More Heroes 2, Tatsunoko vs Capcom, and Silent Hill: Shattered Memories on 360.