If you're advertising on Facebook to boost Fans/Likes you may be paying for Fans that will actually end up reducing your reach and increasing future costs. The following video (Feb 2014) shows evidence through case studies that reveal why its important to have quality over quantity. As the second part of the video reveals, even if you limit your geo targeting to the US, you're still within reach of LikeFarms who's goals are to mask their intentions through Liking literally anything. I just went through and began reviewing Propeller's Likes and found a number of bogus Fans. Some from Egypt. Some from India. Some from Texas... Its a slow manual process but you can remove these. Go to your page. To the right of your cover photo hover over Page Likes, and on the pop up, click on See All. Our advice is to put an intern on this to cull your Fans. Then when you advertise/boost limit your geography and tighten your campaigns by either displaying only to Fans and Friends of Fans, and/or by avoiding targeting broad/common Interests. If you target people who like Cats, you're going to get spam Fans. If you target less popular Interests like American Shorthair Cats you should avoid bad Fans. Its a jungle out there. Good luck.