As it was a slow news weekend and outrage is social media crack, blogs, Facebook and Twitter were suddenly alight with complaints, accusations and tough talk of boycotts.
This was exacerbated by vague and unhelpful responses from Amazon support people suggesting they understood neither the scale of the problem, the legitimacy of people's concerns nor the strength of the feeling they'd aroused.
So, conspiracy theories mushroomed and notorious internet pranksters issued confessions saying they'd done it by gaming Amazon's system for reporting adult material.
The outrage/conspiracy bubble blew bigger and bigger, marshalled by the Twitter hashtag "#amazonfail". Then, just as the theories seemed to be hardening into conventional wisdom, someone at Amazon issued a story blaming the mistake on a "ham-fisted" cataloguing entry by an employee in France who mislabelled some 50,000 books as "adult".
Many of the formerly outraged simply shrugged and moved on, feeling that an evil conspiracy stood revealed as a simple cock-up, but many others clearly felt that their concern couldn't simply be grounded to earth and they continue to condemn Amazon for the processes that allowed the mistake to happen.
They maintain that the sudden retagging as "adult" might have been a mistake but that a stealthier version of the same process has been going on for a while, continues to this day, and amounts to censorship.
They'd suggest the emotional force of the "#amazonfail" weekend might have brought the issue to light, but the surge in anger and subsequent embarrassed retractions have obscured real concerns around a retailer with so much clout.
What do we learn from this? First, that cataloguing and tagging are not morally neutral activities, that database decisions carry emotional and ethical weight and should command senior, sensitive attention. If consumers are being asked to tag an item, then the scope for misunderstanding, maliciousness and the clash of values is huge; if the company does it itself, then it better stand ready to explain and defend its decisions. This effect is even more pronounced for today's vast globe- and culture-spanning internet businesses.
Second, that in a social media world your mistakes will be magnified hugely and instantly. And third, since things like this are likely to happen, you'd better assume they will happen and you'd better have people watching and listening to these social networks - empowered to investigate, intervene, clarify and resolve at the drop of a ham-fisted hat.