I’m getting old
Clerk: What year, make, and model?
Me: It doesn't make any difference, it's a universal part.
I'm surprised at the good luck I've had this year at the local A-Z / A-A stores (NAPA is just a bit farther away, closes at 5pm, and isn't on the way to anywhere I go). I suspect they've had a few problems like the ones you describe. (I've had a few of those as well over the years, but rather than try to drill through the clerk's hardened-steel skull with a dull HSS bit, I've just made up a make and model that I've known would use what I needed).
A few times lately I've needed something generic – fuel hose, brake line fittings, generic PCV valve, stuff like that – and I've walked up to the clerk, told him/her what I've needed, watched the blank confusion wash over his/her face, and then...
the clerk said, "All that stuff is over here," and brought me back behind the counter to look for myself, where I was able to find what I was looking for.
I think someone somewhere realized that the clerks needed to know when they don't know, and let the customer, who does know, do what he needs to do. May just be the managers right in my local area, but it does make it easier to pick up minor parts that I HAVE to have right now.
– Eric