I buy the vast majority of my ink for my ipf8300 new and authorized. I have purchased some carts at a nominal discount from individuals with 100% reputable reviews, usually carts that are going to reach their use by date in a few months (never bought anything expired). Probably bought a total of 7 carts this way over 4 years or so. All were good, in the Canon box, with hologram.
But I recently purchased one that arrived only in the plastic bag, no box as described. So it will be returned. But I have to say, the cart in the bag looks perfect compared to carts purchased from authorized dealers. It it's not authentic, I can't see it. I don't know that it's counterfeit. The fact it's not in the box is reason enough to not take a chance. I can't think of any legit reason it would not be in the box. I'm unaware of Canon making multi-packs of these tanks and packing 2 or more in 1 box.
So how sophisticated are counterfeiters of ink? Is someone actually reverse engineering these things, setting up factory production lines, even making perfect copies of the plastic bag wrapping and making them perfect in every way but for the ink?