The spammed link delivers an offer to install a Dislike button that supposedly gives "the ability to dislike any of your friends [sic] statuses." Clicking Install results in a request for permission to access your personal information, post to your wall, and access data even when you're not using the app.
What does it do with those permissions? It spreads the message to which you you responded to your friends. (Won't they love you for that?)
So what about the promised button? It's still not there. Instead, you're asked to complete an online survey (and that's the heart of the scam) before being directed to FaceMod's Dislike button for Firefox.
The FaceMod button is free, and there's no suggestion that the company is involved with the scam. FaceMod has asked would-be users to avoid 'alternate sources' - the button is available via Mozilla's Firefox add-ons site, but as of this writing is flagged as "not reviewed by Mozilla".
The 'Dislike' scam is the latest in a series that has used a variety of messages to trick people into clicking on links distributed via Facebook.