How to find top selling and profit generating products to buy or to become affiliate marketer?

It is almost impossible. The sites that appear on top in search results, reached there because they did some SEO or bought keywords. How can we find the top selling products that are generating profits to companies that manufacture and to people who are marketing them? I have searched for such products to display on my site for 'that extra income'. I have joined several affiliate-marketing programs, but there is not much money in them. The products I chose to display are neither hot favorites nor trustworthy. The commissions never came. However, I was able to save my site from losing its credibility by adding content regularly that is useful to visitors, but this could not stop emails coming to my mailbox complaining about these banners and links. Some of them do not View the rest of this article