Roger Cicala of lensrentals has dealt with Canon repair a lot, as well as with other repair, for problems that lensrentals staff haven't yet learned to fix in house. He has a VERY SIMPLE SUGGESTION. If you go to the trouble of testing your lens with FoCal or with a home-brew test (even the "brick wall"), you need to send the test photos and the test methods that you used along with the lens, and a list of the defects that you found (eg. "lower left corner consistently soft, see photos #1,3,4..."). Load up your images and text on a $5 thumb drive labelled with your lens SN and your name, and ship it in the box with the lens.
For more details, see his lensrentals blog. But really, this is common sense, service personnel appreciate being shown the specifics of the user's issue with the product, and are likely to look harder when diagnosing the lens's problem - human nature. A lot of people return products with complaints of "it doesn't look sharp" but there may be unrealistic expectations or the product is defective under some conditions but not others, and it is hard to ID some problems in a quick inspection.
I have done that, only I burnt the images to CD, my experience is they don't even look at them, they sent the disc back unopened.
I believe they put the lens on a reference body or rig and draw their own conclusions from the results from those results and that alone.
As for the OP, I did write a rather blunt reply early on in the thread but it got taken down, naughty me! The crux of it though was that these things are tools, they are not hermetically sealed pieces of jewelry. They get dust in them, they get scratches and they end up needing servicing, that is the nature of tools. They are not collectables and they are not precious, they demand to be used as the makers intended, regularly and without compromise, if you do that then you will not only get the best out of them, but you will get dust in them and scratches on them.
Thank you for your responses, although I never did see the first post that was removed.
I always enjoy your "blunt[ness]" on the forum and your posts are very educational.
I fully appreciate and understand what you are saying, and I also agree with you to some extent. Debris in viewfinders is an inevitable issue, and one I fully expect to experience with the ownership of any camera; debris to the point of clouding up a viewfinder after two weeks of ownership is not an appropriate issue to experience for any customer of a new camera product, though. There's still crud in there, I'm dealing with it...and I most likely wouldn't have continued to go on about the issue in the first place had I not received the camera back with another issue which was more mechanical in nature and would/does affect the overall operation of the camera. The finger print was also the cherry on top or the icing on the cake.
Again, I don't feel like I'm being unreasonable or unrealistic about this.
And the thing is, you are absolutely right: cameras are meant to be used, and especially if they are part of the elite 1D line; they are built like tanks and are intended for the worst conditions one can realistically take a camera into. I fully intend on using mine for whatever situations I might encounter. I still, however, expect a certain level of quality control with regards to components and workmanship. Is that unreasonable?