hmm. Steve your question is a little confusing. dropshipping is when you have an agreement with a manufacture or company that will ship their product directly to your customer so you don't have to carry inventory ect. but clicking on an ad and being redirected to amazon or another website selling something is called affiliate marketing. I think your question is regarding affiliate marketing. What you should do is google "affiliate marketing" and understand the term. There is no real catch just make sure you can see the websites traffic and profit per month before you buy.
"Any man can bask in the sunlight, it's the decisions made when the storm hits that define you"