Amazon truly is the website where you can buy anything and everything: books, games, wine – and a Samsung Galaxy S5 case decorated with a pixelated image of a “doctor adjustable angle knee brace support for leg or knee injur”. Yes, missing the trailing y.

That last product comes courtesy of the third-party seller “my-handy-design”, which has caused a stir in tech circles after the bizarreness of its product line was first noticed on Sunday.

The company has more than 30,000 phone cases available for sale on Amazon.com, including an iPhone 6 case with a picture of “Male hands with soap dispenser use in the restroom”, another featuring an “Irrigation pipe in dirt trenches for sprinkler system” and – for those with a particularly weird taste, even in these weird times – one illustrated with an “adult diaper worn by an old man with a crutch”.

Why do it? Because the power of scale can be a lucrative thing. The company’s algorithm takes royalty-free images from any source it can find, automatically mocks up a phone case using them, and throws them up on Amazon in their thousands. Sure, the vast majority will never sell, but it costs nothing to make the listing.

And if, through random chance, you happen to create a phone case that someone searching Amazon actually wants – perhaps decorated with a “New chrome faucet in master bath tub” – then it’s the work of minutes to print a case with the picture and post it, making a small profit in the process.