The Verge did an interesting
article on the hijinks a group of romance authors got up to in order to game Kindle Unlimited payouts. It's kind of depressing, but then I guess there's a reason you don't want to see how the sausage is made.
One interesting point: They say that one of the fallouts of this hacking of the system is that it is making romance more misogynistic. I don't know that I buy that. I know very little about romance, but within the article, they don't really support their claim.