1. The company make interesting advertisement so it could get attracted by people. The people might think that the products is good so they buy more and more. When they don't need it anymore, they start to throw it away!
2. I think they just waste the money and don't think about the negative impact of the products. In the advertisment, if it just show about the positive impact of the products, surely there will be alot and alot of people want to buy it! But if they advertise both about positive and negative impact, surely the number of people who want to buy the products will decrease and something, people don't even want to buy it. I think the teacher at school could tell the children about the negative impact of the products and that child can come back home to tell his or her parents and the parents will tell their friend, it keep go on and on so the people will know about the negative impact of the products and don't waste their money with a lame products.
3. Yes ofcouse, they all talk good things about their products and use actress or model to introduce there products. I love Etude House  lipstick the most because they use Lee Min Ho, my idol to make the advertisement :D