Well, since you can normally spot most of that stuff visually, the only inspection is that of a skilled operator.
The chances of a skilled operator mixing something like that are practically nil, no offense.
I wasn't talking about myself Karl- I'm wondering about SE distributors, in particular. One SE place I get film from prints the RGB levels on the can tape itself. But others do not, so I will often send those rolls in for clip testing anyways- I rarely act as a DP, so the amount of film I actually shoot when I do get the chance is low enough to be able to afford the scattered clip test. Considering though that different emulsions have different base fog densities, I was curious how thorough an inspection the labs will do on the film. For example, if film was bought from a SE reseller that came from a student film- I would necessarily trust that the can would match the actual film. So when they do the clip test, if they did not actually inspect the emulsion to ensure it matches the can, they could be providing an inaccurate Dmin to compare to. Also, physical damage such as pressure marks can be there, but not in image area. Basically, problems can be there beyond basic age fog.
So how in depth do they get when they clip test? Are they checking the edgecode to make sure it matches the can, then comparing it to the Dmin values they have for that particular stock? Are they doing an eye inspection to, or is it just thrown onto the densitometer and given no in depth visual inspection, to ensure no physical damage or abberations outside of picture area? That's more what I'm getting at.