—maybe the lesson for marketers is simpler than it seems: Facebook likes are only as valuable as the actual sentiment behind them. That is, unless people genuinely like your posts—in the original sense of the term—getting them to hit like on your brand page isn’t going to do you a lot of good. And maybe that's the way it should be.Slate examines how and why Facebook has changed the reach of Facebook likes and what that means for marketers, especially those with small businesses.