So while I have bought refurbed bodies, I've never bought a refurbed L lens. I can see why someone would return a body because it did not meet their needs, but returning an L lens I would find less likely for this reason as its pretty clear what a lens is able to do upfront.
Reason behind my train of thought is the below:
1) Canon refurb stock to my knowledge is generally customer returns in the 30 day period or dealer demos
2) I've heard lots of people who will do sharpness tests with brand new lenses and return them if they do not match some of the reference tests online. Or sometimes they will order multiple copies and return the less sharp ones.
3) Most of the time due to copy variation less sharp copies are generally considered in spec (i.e. look at lensrentals data), and thus Canon would not adjust it
4) Thus, when buying a refurb lens and thus a customer return, there might be a higher probability you would get a less sharp copy than if you bought new
Is this reasoning crazy, or do others agree?
I do know many people are happy with refurbed lenses, and I am not talking about getting a lemon here, just a lesser chance of getting the brightest bulb of the bunch. I've also heard quite a few stories of people getting refurbed lenses with a lot of dust inside, though it is unlikely that would affect image quality.