You need to be careful what you listen to repeatedly because you might eventually mistake the lie for truth.
Take this marketing ploy as an example.
Branding often involves retelling the same fictional story again and again, until people become convinced it is the truth. What images come to mind when you think about Coca-Cola? Do you think about young healthy people engaging in sports and having fun together? Or do you think about overweight diabetes patients lying in a hospital bed? Drinking lots of Coca-Cola will not make you young, will not make you healthy, and will not make make you athletic — rather, it increases your chances of suffering from obesity and diabetes. Yet for decades Coca-Cola had invested billions of dollars in linking itself to youth, health and sports — and billions of humans subconsciously believe in this linkage.
— from the book 21 Lessons for the 21st Century