There is a Report button on every listing.
However, eBay does not take sides on authenticity between members.
Instead it uses the VERO process which involves owners of trademarks and brands to police their own products.
If you ever get told to take down a listing (or have it taken down) don't try to relist it.
Your selling account is likely to be closed.
If there are a lot of complaints (including Disputes, but not feedback any more) eBay may decide to close an account as being more trouble than it's worth.
And of course, we often see complaints from buyers who have been told by eBay the product they bought and paid for is no longer listed. Annoyingly, eBay doesn't tell the buyer how to get the payment back . (Hint-- Paypal.)
What they don't respond well to is reports from members who are not involved in a transaction, although those may be used as part of the 'too much trouble' account closing.
