I almost always have my part numbers looked up on their system before I ever walk into a parts store. If that refuse to go get the part based on my number and ask what is for I reply with "1921 Duesenberg". They always ask me for the part number I tried to give already after that.
I'm the same way, I have my crap together before I even head down there. In fact, the only reason I even call is to make sure they have it in stock, you can't always trust what their website says. I went to an O'Reilly's once that told me they had a thermostat for my 85 broncoII, it was on the other side of town, and in the friggen ghetto. I get there and she says she looked at their system wrong and it's at another store. Needing to get my junk running, I haul it over there only to find out they don't have it either. Pissed off I go across the street to Advance, and a Hispanic who knew limited English had no problem going to the back and getting my part. In and out in less than 5 minutes, imagine that. I later found out that he was their Spanish speaking only parts guy for the Hispanic customers. I ended up complaining to Oreilly's corporate and they sent a gift card. I banned O'Reilly's until they opened a new store a couple miles away from me. The manager lives about a mile from me, and wheels a 77 bronco. He has a good crew, and I'm hoping he keeps them. It seems like a parts store will get a couple of good parts guys that know their stuff, then next thing you know some idiot has taken their place.