I have heard many stories online where customers bought new graphic cards/cpus/camera gear from 'Sold by Amazon.com' but instead receive used ones. Or receive different cheaper (older generation) products.
It does not seem to be a good place to buy or sell expensive items.
I've received two used products from Amazon (bought as "new") in just the last year. First was an espresso machine. It wasn't even cleaned - coffee grounds were everywhere. The second was a robot vacuum that had a full dust bin. After turning it on, I could see the previous owner's home layout in its memory. In both cases, the product still worked and it wasn't worth the hassle of returning. Whenever I buy something, I make sure to check for non-Amazon alternatives, even box stores.
Going off Amazon's just not worth it in my experience. Slow and/or expensive shipping (week/weeks vs 1-2 days), no/limited returns (4wheelparts for example deducts shipping costs from a return if you had free shipping, which is already factored into thw price so they're double dipping), no canceling often (4wheelparts again), worse search/interface, and no 5% back from my card. I only order outside Amazon as a last resort these days.
That can happen anywhere, through any medium (e.g. bricks in a box instead of a PS4 from Best Buy). It seems amply evident, despite the recurring horror stories on HN, that most customers are having a pretty decent time of using Amazon.
In any case, isn't the author's scenario pretty bizarre? I had no idea that Amazon served as a mechanism for selling one-off small scale used items. Further the author mentions that it would be cheaper buying and selling than renting...only this is precisely the risk you need to factor in buying and selling (which could have been a fake cheque, getting rolled during the exchange, etc).
I bought a lamp for a rear projection tv a couple years ago. It burned out after a month. Amazon let me return it, but charged a restocking fee. That would've been fine, but I haven't been able to review the product for over a year now.
Newegg has problems too. All my friends have RMA horror stories with them, mine is having to pay $50 and shipping because the plastic PCI-E retention clip broke when I was disassembling my new computer with DOA motherboard for an RMA.
Also, Newegg gave up on maintaining their reliable filtering tools for third party sellers.
Mine is returning a phone, and having them ask for my Gmail password three times. Maybe it's my fault I didn't disassociate something prior to factory reset, but the phone was fine. And new. They claimed they couldn't complete the return until they had full access. That alone tells me they are selling used phones as new. After I refused, they told me to just change it to something temporarily so they could log in. I demanded the phone back, and promptly donated it as is.
You had to disassociate your own google account before factory resetting. If you forgot, then yes, it requires the previous owner's gmail password to continue.
It does not seem to be a good place to buy or sell expensive items.