Advertising helps the advertiser if it results in a sale - it doesn't matter if the sale helps the viewer.
If it resulted in a sale, then that means by definition it helped me find a product or service I wanted. If I made a bad decision in making that purchase, that's an orthogonal issue.
If it resulted in a sale, then that means by definition it helped me find a product or service I wanted. If I made a bad decision in making that purchase, that's an orthogonal issue.