How many times have you seen somebody on a messageboard rant about the uselessness of their local parts store? Maybe I notice it more, because I'm one of those guys behind the counter. Not always, but sometimes I think it might actually be the customer. Here's my free advice.
Try to know what the vehicle is that you're working on. Don't guess at the year, they're not "all the same". Year/make/model is a good starting point. If you're working on drum brakes, measure the diameter at least(sometimes you can read the max diameter on the drum) there's almost always 2 choices. If you don't have the car with you, write down the VIN#, at the very least it can tell you the model year, and engine choice(on domestics). Don't get upset if we're not experts on your particular vehicle. We need to know a little bit about any year,make, model that rolls in the parking lot. Only the dealership guys can be specialists, in the aftermarket we need to be generalists. Most important, don't get bent out of shape over questions. What might seem like a stupid question, is what the catalog designer thought would be the easiest way to identify specific options. We're just trying to find you the right parts. Taking back returns, is a pain in the ***.
Years ago I remember a co-worker telling a customer
1- I've never seen your car before.
2- I don't know how your car was optioned.
3- The only clues I have, are what you've told me.