All get field striped, inspected, wiped down (at least) and lubed. More if needed. When picking up a new firearm, I always bring my range bag with cleaning supplies.
This does several things for me.
First, it makes sure I know how to field strip and operate it properly in case I have issues on the line. This includes magazines and other doodads.
Second, factory "lube" depends on the manufacturer. Some handguns came covered with "preservative". When I lube it, I know what's on it.
Lastly, I know it's cleaned and lubed. There are plenty of stories about people buy new guns that are very dirty. Some allege the guns are "used", some suspect the LGS staff shot it or a potential customer did and decided not to buy. I may not check the oil level or tire pressure in a new car, but I do check the odometer. Last time I looked, handguns don't have "odometers".
Anyway, that's what I do with my guns. As always, YMMV.