Disclaimer: The materials provided below are informational and should not be relied upon as legal advice.
eBay and PayPal have an internal dispute procedure that you can use to report this and get your money back if the seller advertised a genuine item and sold you one that was counterfeit.
Yes, your credit card company should refund the money you spent if eBay doesn't.
That's if you asked about the genuineness AFTER you bought it and got an evasive implication that it wasn't genuine. If you asked BEFORE you bought it, then you knew the seller wasn't claiming it was genuine.
Don't worry about eBay's obligations to do anything about any other "similar" orders.
Avvo doesn't pay us for these responses, and I'm not your lawyer just because I answer this question or respond to any follow-up comments. If you want to hire me, please contact me. Otherwise, please don't expect a further response. We need an actual written agreement to form an attorney-client relationship. I'm only licensed in CA and you shouldn't rely on this answer, since each state has different laws, each situation is fact specific, and it's impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue.
NO, you are not required to report it unless you want your money back. Let eBay take care of eBay. You should not get embroiled in copyright/counterfeit/trademark disputes.
Do not resell your counterfeit items, as that would be willful infringement and there are serious legal and criminal penalties.
We are not your credit card company, and we don't make the rules for them. Talk to them about chargebacks. Most have challenge procedures. They will let you know if you can confiscate the counterfeit and still get a refund. The terms of any purchase agreement with the vendor will have a bearing.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.