I understand why you feel like that. A lot of it is just motivation with no real depth. Real advice usually comes from people who are actually doing it, not just selling courses. Look for sellers who share specific things such as numbers, mistakes, or processes. Honestly, the best way is to learn the basics, test things yourself, and be around a small group of active sellers where people share what is working now. If someone will not even show proof or real work, that is already your answer, to be honest.
You know it is a scam when they do not tell you their brand or product they are selling, because you could easily use Xray with Helium 10 to see whether they are actually walking the talk.
Amazon University and ChatGPT are all you need, along with practice by yourself. Keep testing and trying until you figure it out. That is what I did, and the improvement was huge. Do not pay anyone for anything.