sib, I see the same thing with my girlfriend at the snowboard shops. For two months a year over the last 5 years, I spend countless hours doing very detailed technical analysis on snowboards and the upcoming lines that are being offered by the various manufacturers, so I am extremely knowledgeable about the technical aspects of board construction and what is out there on the market today. As a result, much of this has rubbed off on my girlfriend and she is extremely intelligent when it comes to equipment.
I find, though, that it still takes about 15 minutes before the guys at a shop stop talking to her like she's a "dumb blond" who spends her days on the bunny hills before retreating to the lodge for an afternoon of hot chocolate.
Many shop people are arrogant to begin with. On top of that, pretty much all snowboarders have at least a bit of cockiness when it comes to riding. Put the two together and you enter very dangerous, annoying territory.