If they can count to 10, speak semi fluent english and spell four letter words they meet GC's standards. Seems like that's the only qualifications 90% of the guys at GC I have dealt with posses.
I honestly hate those guys in pro audio at GC, they really don't have a clue what the hell they're doing. After being a member of this board for quite some time, I walked into GC and asked a few of the guys "What's the best Rap Microphone" just to get a kick out of it. My god! The many different answers I've heard. Those guys need to be trained if they are going to be answering questions, if not they should just be quiet cashiers.
As in your situation, I absolutely hate it when someone is talking about relative issues as if they're facts and don't hear how foolish they sound.
I always ask silly questions when I go in there just to hear the answers they give me. My favorites to this day are:
ME: "What's the difference between mattress foam and auralex?"
GC Guy: "Mattress foam gets older faster"
ME: "What's the best Rap microphone?"
GC Guy(s): "this one"
ME: "What's the best compressor you guys carry?"
GC Guy: "Antares AVP Vocal Producer"
GC Guy: "...well what preamp do you use?"
ME: "Depends, Studio Projects VTB-1 mostly or a DMP3"
GC Guy "What the hell are those?"
ME: "Uhhh.. Preamps
"