Facebook: "Like/join to find out" scams

Those who actively use their Facebook know that some groups require you to become a member in order to gain access to particular information. Many groups project silly riddles or questions, but will not divulge the answers until you either "like" or "join" the page. This is an easy way to hook interest and get people to follow a particular group merely by exploiting user's curiosity. This function seems trivial, however I contend that it is unethical, harmful, and distorts the Facebook landscape.
Facebook profiles are visible reflections of users, meant to accurately identify people, friends, and interests. Your actions on Facebook are explicit, as other users can view your profiled identity and the entire network of labels with which you are publicly affiliated. Users make conscious decisions about whom or what they associate with and many attempt to accurately project themselves through their profiles. It is counterintuitive that somebody would choose to join a group that they know little to nothing about and explicitly associate it with their profile for others to see, when it is likely not an accurate reflection of their self or interest.
This trend confuses the validity of people's profiles and is merely a surface level marketing gimmick. People should know what they are joining and why they are joining any particular group, and not merely find out what they have associated themselves with after the fact. Many of these types of groups are purely detrimental and turn out to be scams, never really providing the user with any useful information. The dilemma seems trivial because Facebook is merely a virtual platform and only an approximate extension of self, but apply the same logic to a physical world situation. Would you actively associate yourself with some social group (team/club/event) that you knew nothing about just to get some tidbit of information? Likely not, so why do it on Facebook? Even if the consequences are not as dire, the ethics remain the same.