The OP needs to understand what refurbished may mean and the process in getting to that definition. I used to work for an electronics manufacturer and many of the products, which had dedicated use, could cost $50,000 a copy. We might have sold 200 "copies" a year. Even at that number of copies a computer routine was developed that did all testing, and it did it in about 5 minutes. The imbedded PC in the device was far more complex than a camera processor. Now, since several hundred thousand copies of a given camera are made, perhpas even millions, I would suspect that Canon simply looks at a camera cosmetically as a 1st step, then hooks it up to a camera for a full "inspection". Depending what it finds then a decision is made on what happens. If the shutter clicks are low and the camera is clean, very little additional time is spent on the camera. It gets boxed as a refurb. If a specific problem is noted, say a bum shutter or main board, the decision may be made to scrap the camera. The profit margins of a camera is quite high, thus a major component replacement can be accomplished and a profit realized, so long as the camera is cosmetically good.
Having said that I have neighbor who is a district manager for a major box store. He returns a huge number of cameras annually that people find too complex or just isn't what they expected. A very common return is a person who had a 35mm film camera 15 years ago, uses a P&S today, but decides to get back into photography with a DSLR. He anticipates using his old lenses, but had never heard of crop factor and doesn't like the perceived field of view after purchase, hence the DSLR is returned. Too complex, not what is expected, etc.; none of those cameras can then be sold as new. The particular box store attempts to sell as open box at about 10% off, but after a month or so they go back to the manufacturer.
