For romance readers, Kindle Unlimited (KU) has been a godsend. These readers can race through at least a book a day, gulping down stories about unexpected pregnancies, arrogant millionaires and bad boys in need of taming. KU means they can read to their hearts’ content, while the writers can make a lot of money. Authors who self-publish through Amazon’s Kindle Direct Publishing (KDP) Select programme have their books automatically enrolled in KU. Every time a reader opens a KU book, the author is paid from a communal pot of money – one which less scrupulous writers have looked to game from the start.

When KU was launched five years ago, authors were paid by Amazon from a monthly pot each time more than 10% of their book was read. Scammers descended, publishing books running to just a handful of pages, filled with worthless text but earning their “authors” money each time they were clicked on.

So Amazon changed the system. Now, authors are paid depending on how many pages of their books are read. The more pages read, the more money made. And there is, potentially, a lot of money to be made: the monthly pot in February was $23.5m (£17.7m).

But where there is money to be made, there are scams to be run. Last year, several KU writers noticed a rise in what is known as “book-stuffing” – authors publishing extraordinarily long books, filled with vast amounts of questionable additional content, along with an incentive to head to the last page.