Regarding marinyork's comments:
It is, admittedly, difficult to know who you're dealing with when you first walk into a shop. Try to do a bit of research. Usually, you'll end up at a certain shop b/c of a recommendation ... and this is the best way to "pre-screen."
Don't necessarily "walk out ... and never go back" if you can't understand what the employee is trying to tell you. I've had this experience with many novices who, because they can't follow what I'm trying to tell them, get defensive and think I'm trying to bilk them. There is a certain amount of trust that needs to be built ... and it goes both ways.
There is the problem that many bike stores employ kids who, while they may be bike enthusiasts, are not professionals. They will have a certain focus -- mountain biking, say -- but might not have a clue about, or care about, your needs.
Most importantly, a good shop will have top-notch mechanics who are capable of working on everything from a Sturmey-Archer 3-speed, to Campag 11-speed, and most everything in-between. They won't bullsh!t you if they can't.
A decent LBS these days knows that these things are their only hope of surviving in a market that includes internet shopping and big box discount stores.