You need both a good funnel, and a message that provides value to a user. It has been crudely expressed as "do you get your user laid", less crudely as "make your user look cool". If you do this, then they'll share your service to all their friends for free. In our case, someone is proud to ride 100 miles, and they'd like to show it off. Our tool let's them do it, so they paste it around on facebook. It's all about your value prop and how someone feels sharing that with others.
Well I think that's an interesting point—this isn't what I typically think of with facebook advertising (i.e. "like" shopping). Figuring out a way for users to demonstrate to other users the value of your product is pretty much ideal, though—it scales very well and I would imagine it's much, much more effective than traditional, sidebar advertisements. Why don't they emphasize this more? I would assume likes are more valuable to them directly as opposed to advertisers....
More like "We will annoy you with social network notifications, sell your data, and pollute your facebook page".
EDIT: Certainly not everyone, but if you ignore the downsides you're not spending your money well. Being polite with respect to interacting with your customer is value in itself, and you cheapen your brand by including social buttons. Even the choice of button matters: including a share button treats me with more respect than like buttons AND provides a much higher quality recommendation for your brand per click, even if the clicks go down. If you're advertising on Facebook without testing which provides better numbers at the end of the quarter, you're probably not spending your money as well as you could.
And why are you so negative and hostile towards something over 1 billion people signed up for?
And since I acknowledge that it must work for someone (just like Nigerian Prince Scams work on someone), the more important question is, "and is it worth the effort and cost?" I could spend weeks building a social following for a local business, or I could run a coupon deasl.
2) It's FREE. Create a facebook page for your business, upload a photo, copy paste the like box code and call it a day. Jesus Christ what do you have to lose?