The ability to "like" people and businesses can be used as a trust network. it's standard practice for people to ask their friends for recommendations when choosing a doctor, lawyer, or other service providers. None of the people I know who have small businesses advertise. They rely on "word-of-mouth" to get new clients. Facebook "liking" and future derivatives (perhaps unlike, recommend, and complain-about) is the Internet equivalent of "asking your friends."
Most people have 'likes' that years ago were groups that were silently transmuted into pages by the group owners, and since then silently turned into public 'likes' by Facebook.
In other words, it's a very poor trust network, because no one is using it that way. Most people 'like' a lot of stuff in a casual or even joking manner.
Unlike, recommend, and complain might be useful, but Facebook is an advertising platform, not a recommendation engine. I doubt they'll make that transition, because it would cut in on their revenue to let people clearly mark advertisers as unwanted.
