My understanding is that not even that is safe. Amazon mixes stock for the same sku product from all their suppliers, so even if only one of them is selling fakes, you can get one.
Not even "Ship from and sold by Amazon.com" is safe for the same reason I believe.
To clarify: This is based on experiences I've had en AmazonES buying things directly from Amazon (Gillete razors from the top of my head) and them being obviously fake.
Also from previous discussions in HN
This happened to me with a Steam Controller. Ordered "Ship from and sold by Amazon.com" and received one without retail packaging and accessories and was defective. Had no issues with it getting replaced by Amazon. I assume some sellers use FBA to let Amazon deal with customer service so they can get away with selling bad products.
Really wish they wouldn't mix SKU and stock. Perhaps its cheaper for them and if the customer notices they can replace it and still come out ahead. But it doesn't seem fair for someone who can't identify a fake product.
I believe Amazon does co-signing when you buy "sold from Amazon". Are you sure they also do so when sold directly through supplier , and not under prime ?
If it's not fulfilled by Amazon, then it's not coming from Amazon's warehouse. It could be subject to counterfeit by the seller, seller's supplier, or possibly even the sellers fulfillment center.
My understanding of FBA is that each SKU can have multiple suppliers, and stock is assigned to its supplier as it arrives in the warehouse (e.g. 250 Anker chargers with SKU ABC123 from AnkerDirect arrived May 22nd and are stored in warehouse X, unit Y, location Z). An order for a SKU from a specific supplier (e.g. ABC123 charger from AnkerDirect) will be taken from that stock, and the quantity remaining is reduced accordingly.
So, to answer your question: if that all happens, and assuming AnkerDirect doesn't have shady stock, then yes, it should be genuine.
It depends even more on whether there are any sources other than Anker Direct for those branded products. If they're the only source and Amazon is their only channel, then any other seller is either counterfeit or purchased through Amazon and is now trying to resell.
I'd purchased several PowerLine cables that all died within a month or so of purchase. I attributed it to being a cheap cable.