It's fun if the sales dude knows Persona from Disgaea, but I'm way more interested in just having a friendly encounter with reasonable people in a clean space. The reality is that I run smack into brand zealots who are trying their damndest to upsell me on everything in the store.
Sometimes that creeps me out. One time I was in GS when two geeks started geeking out about how SquarEnix was once SquarEA and I wanted to crawl into a hole even though I knew every aspect of what they were discussing. I just want to buy my game with as little discussion as possible.
It was cool when the sales chick knew Katamari Damacy though, that's something that wouldn't have happened at Best Buy. The difference was she just made a passing comment and didn't have an all-out geeksplosion about it.
edit: The other difference was she wasn't obese and had a vagina, obviously. People like that are given more leeway by everyone but demi.