For 20 years, the Billboard charts were easy to manipulate. By paying radio stations and some retailers, record labels could push an act to the top 40, which would increase sales. People liked buying what they heard on the radio, and the radio played what they thought people were buying.
Billboard changed their methods about twenty years ago, and overnight the acts on the list changed. Suddenly, it became clear that what we were listening to wasn't what we thought it was, and as a result, the marketing of music changed forever." Read The Rest.