No, I don't misunderstand Amazon's role. When I wrote that Amazon will do nothing in regards to counterfeit goods, I meant that they offer no recourse for counterfeit goods purchased from third party vendors. No refunds, no "satisfaction guarantee" or anything of the like. If that has changed, then I apologize. It's been about seven or eight years since this happened. I had to eat about forty dollars on that purchase.
There are essentially three types of Amazon purchases, which boil down to two as far as the return policy goes. The first is where Amazon is the actual seller; perforce, the order is also fulfilled by Amazon, and all standard Amazon return policies apply. The second is a purchase from a third-party seller that uses Amazon for order fulfillment. In this case, all of Amazon's standard return policies also apply. The purchaser is still relying on the actual seller to provide the goods as claimed, but will have pretty good recourse in the event of dissatisfaction. Amazon's return policies are very liberal, and I have zero doubt that if I listed "counterfeit goods" as the reason for a return on an Amazon-fulfilled order (whether the seller was Amazon or a third party), I would not only get a refund of both my purchase price and shipping, but the return shipping would be paid for by Amazon as well. It's as close to no-risk as you can get.
The third type of purchase is a straight third-party sale, where Amazon is merely providing the means of transaction, but is not involved in the actual sale or fulfillment. In these cases, the seller's return policies apply. Technically, those policies are meaningless in the event of a fraudulent sale; under the law, the sale would be void, and you'd be entitled to a refund of your purchase. However, the problem is enforcement. Good luck trying to get a refund from a seller who knowingly defrauded you. At this point, the most Amazon would do is enter as mediator (if they did that much), but their own liberal return policies wouldn't be available to you.
Basically, you're always best off going with a seller you know and trust. Going with an unknown seller through Amazon with an Amazon-fulfilled order is a calculated risk, but with a pretty good safety net. If you purchase straight from the unknown seller (even through Amazon), all bets are off.