I suspect a primary meaning of "counterfeit" on Ebay is, "Manufacturer's profit margin is high but they don't want a secondary market to exist".
See also, exercise DVDs, which enter the used market in an enormous tidal wave at the end of every February, but companies like Beachbody would like to pretend that there is an army of pirates counterfeiting something for which there is already a vast unwanted supply, so Ebay plays right along.
The water filters are very much like exercise DVDs. They are incredibly cheap and simple to make, but GE has a razor-and-blades business model, or perhaps better stated as a printer-and-ink cartridge business model, where their profit is in the overpriced consumables. So they have that chip, basically just to enforce use of their own product. Some of the printer companies do that too.
Then there is the collectible market, where the situation is slightly different. Every counterfeit claim I have ever gotten has been on a legitimate, genuine item. I got a takedown from Hershey on a used, empty chocolate tin, I got a takedown from some movie studio on a Scholastic fan-book from the old Book Fairs. Obviously neither of these were fake. Who would bother?
I got a takedown from Trends Intl claiming a poster was fake. That one ended better though. Because I was in a salty mood that day, and I fired off a nasty email to Trends declaring that I would remove all their posters from my brick & mortar comic shop if they didn't reconsider. And you know what? They sent me an email and apologized. No kiddin'. I framed it.
See, these people just have bots or crawlers or interns or whatever, who just do buckshot searches for their company name and file claims on everything. Complete abuse of DMCA but Ebay plays right into their hands.
