I still don't totally agree with you. There are some products that are already in high demand naturally and without advertising them, the product will sell. For example, in my country the food garri without advertisement and proper packaging sells more than the food noodles which is properly packaged and advertised.That is when you have created a very big demand for the product. You need some marketing and advertisement to do that. if similar products are already in existence you need to tell people the reason why they should patronize your own brand.