For twenty 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.
The New York Times bestseller list is even more easily manipulated than Billboard ever was. It doesn't cost much to scam it and it's pretty straightforward to buy your way onto the list (I know authors who have done this and consultants who sell this service.) You can hire a bunch of old ladies who will go into the 'right' stores and buy books on the right day. As a result of this distortion, the books on the list get more promoted, and thus sell more copies. It's not pretty but it's true. The Times is well aware that this is going on, that the list isn't accurate, but they persist in publishing lists that are demonstrably wrong. (I still find this amazing, but it's true).
Manipulating social networks is easier still. There are firms that manipulate which stories are posted and which blogs are linked to, and for years there are firms that have worked to manipulate which links come up higher on the search results as well. As these signposts become more, not less, important, there's a significant market opportunity for someone who can, as Billboard did, clean up the charts and make the payola worthless or at least more transparent. In the meantime, be skeptical.