Some of those ebooks were actually promising, but then it requires some work too. If you want to sell something then you will need to learn PPC, making sites around the product, getting visitors, knowing seo etc. Some ebooks that i read/bought had information about the product that could be sold and become rich [$$$ ], still the other things told above has to be done, else you won't see any sale
Basically it goes like this - someone spams a chatroom or something similar and makes around $568.76 <<< note the very exact amount The next day they throw together a PDF with the amount they made as the title. They haven't been doing this method for months and earned a stable income, they just did it a few days ago. They make another $500 selling 50 x $10 ebooks. Quite easy.