The easiest way is to test through small, low-cost campaigns. For example, you can create a short post, video, or email explaining what the product does and who it might help, then track how people respond. Watching clicks, comments, and messages gives clues about interest. You don't need big ads at first; even free tools like social media posts or polls can show if people care about the product. Some people also try small paid ads to test headlines and images before spending more. This helps avoid wasting money on products no one wants. What simple methods do you think work best when testing new affiliate products?