"So, I hear sex stories sell, so I think I should do that. What type of sex story sells best? Also, how short can it be before people stop buying it? Is 1,000 words enough, or should I make it 4,000? How quickly can I crank out 2,000-word sex stories, and how different should they all be before people stop buying them? I don't want to be bothered reading any erotica to see what it's about, so just explain to me what the most profitable ones all share in common."Honestly?
As a reader, this kind of discussion skeeves me out. When I see a writer baldly announcing, basically, "I don't give a crap about the story, or anything else, I just want to know the recipe for soaking money out of the marks" it makes me want to never, ever read any of their mass-produced crap, ever, let alone buy it.
Writers, please be aware that open greed is noted, and readers don't really like being seen as sheep. Especially not sheep watching the farmer trying to throw together the easiest sheep ramp at the lowest creative cost.
Pretty nasty, this "must make dollars" attitude amongst writers.
No, I don't believe writing is 100% inspiration, and, yes, I firmly believe that art cannot exist with economics. Sure, we all want to be read, and to sell. But, in my opinion, it needs to start with a good piece of writing.
So, if you are asking "what piece of crap can I throw together to make you buy it?" the answer is none, frankly.
Go find some boglands to sell to tourists.