This is part of the reason I am wary buying refurb lenses from Canon. If they send back obviously broken stuff from repair and say it is "in spec," there is a good chance they would sell same said broken stuff in their refurb store as according to them it would be "in spec"...
Well this part of your reasoning is unfounded, in that case. They use rigorous specs and testing (http://shop.usa.canon.com/shop/en/catalog/CusaMiscPageView?langId=-1&storeId=10051&catalogId=10051&file=refurbished/refurb.html
), I have never had any issue with refurb lenses, the same 1 year warranty applies, and this particular lens was bought in a store
. Many even say buying refurb is safer since these have undergone rigorous testing.