If, for some reason, you fall for one if these scams, make sure to remove any references to it from your profile and delete any bad app that has attached itself to your Facebook account. Do that by going to the small arrow on the top right of your screen, then Account Settings > Apps. Also, check whether you may have unknowingly “Liked” bogus sites or pages by going to your Timeline and clicking your “Likes” icon at the top of the page. Any Likes you don’t recognize? Unlike them.