I think both you and your friend are neurotic.
Regarding her *spotty* mirror, the actual dust particles may be stuck inside the pentaprism housing under the flash. Cleaning the mirror won't help and unless there is a LOT of dust inside the pentaprism housing, she may be getting needless and expensive work done for nothing. It's a big job to open up and clean the pentaprism housing. It's nice to have it clean but if you can't keep it clean and it doesn't affect your photography, what's the point?
Regarding getting nervous changing lenses frequently, that's compulsive behavior. That's what the camera is built for. When you change lenses, just make sure you do it in a relatively clean area, and make sure you do it quickly to minimize dust ingestion. If you do get dust on the sensor, you will see it on your images and you can blow it out with the rocket blower. If it gets really bad, you can get special swipes to clean the sensor without having to send it into Canon.
I've unfortunately got dust inside the pentaprism housing of my 5D. Am I annoyed, Yes! What do I do? I use a rocket blower to make sure the mirror and sensor surfaces are clean and carry on. (I have swipes to clean the sensor but don't really think it is necessary.)
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Ed, you are awesome! Can I have you make a house call to my friend before she turns me into basket case or have me commit her into institution!!!! She made me look at the picture of her kid blown up to extreme proportions on my monitor, I could see every pore on this kid's face, I swear I could see no spots. So I think you are right, she just needs to try the blower...shops were closed today, we could not buy it, so before I knew it she e-mailed Canon, and of course, they e-mailed back that they can fix it for her...for a fee. That made me nervous about how I change my lenses as I am sometimes taking my time with them, I am not that fast yet, I suppose I worried that my clean 40D may have the same issues one day, Ugh...
T-H-A-N-K Y-O-U very much, you have no idea how sweet your words read, LOL. I have never thought reading I might be neurotic might make me happy[:O]
You just made my day...and her, I am calling her right now to go and read your post.