Scam artists may try to implant an idea that your own mind expands upon and draws an (incorrect) conclusion. They allow you to believe what you want to believe. They may not directly claim their product grows hair, but they use suggestive phrases to plant an idea and then allow you to convince yourself that their product will cure your baldness.

You should approach any product with skepticism and train your mind to read exactly what is in the advertisement and not what your mind might "interpret". Read the small print too.