to elaborate, this is a old facebook trick. You get a friend request from some hot looking girl and you accept cuz you are horny and in your 20's and it says they are actually already friends with your pal Dave! they even chat with you a little bit sometimes, very blandly and generically..

but now they can see all of your friends, posts you have set to friends only, etc. It's a wedge to bypass the host services privacy settings and nothing more. Those accounts can see things that google can't see and there's money in them there profiles. They use the fact that they are now friends with you AND Dave to more easily target people you both know and the botnet grows.