It's more about what you can easily sell, you really can't go by marketplace stats. They don't depict the true sales of what's selling.
For instance, Clickbank, only show sales affiliate makes. I can make 100000 sales, but it won't even register in their market place. Now If I created an affiliate ID in Clickbank and then sold my own products, I would rocket my stats in clickbank to the first page in popularity.
I did a few tests with a few affiliates and made a bunch of sales for 3 different people, tossed them all 2-3 sales, in 2 days. By tossing 7 sales to affiliates and not myself, I raised my ranking from the back of the pile to 26th overall in software in services in 2 days by tossing sales. If I tossed sales for a month, I would probably rank #1 in overall sales. So those market place stats really don't show what's selling or not selling.
So when you do affiliate marketing, you can sell multiple products, it's not a one and done, just collect the email addresses and build that relationship with the clients and then offer them multiple products, products that pay well and products that don't pay well, it doesn't really matter, revenue is revenue. It's the strategy on how you go about it, that makes you successful or not.
Always capture the email (the most important thing) - Know your buyers and market to those buyers.