I think people need to re-look at face book .I just randomly searched 'buy shoes' to find an example
https://www.facebook.com/shoesonline
1673 members , are you telling me that the people that like a page called 'shoesonline' would mind if they were then sold to ??
I bet who ever owns thos page will love me


Let me be more specific. It is a very unsafe assumption that people are on Facebook to buy. It's also quite an unsafe assumption that people who follow a brand want to buy.
First off, people use Facebook in a social (old meaning) context. They are there without a suit on, mainly to share with friends and family.
They may wish to express a like of some brands, but these are likely to be brands they're happy to be associated with by friends and family -- B2C, aspirational, brands they consume/use as a private individual. I might follow Manchester United or Mini or Ferrari or Oakley or Ducati or whatever. I like people seeing me Liking those. I won't follow Persil, Domestos, Fairy Liquid because although I buy thos ebrands frequently I don't want to advertise that fact to my Friends.
That I follow Ferrari and Manchester United does NOT mean I am interested in buying though, nor does it mean I want to receive pushy marketing messages. I AM interested in news, updates and the OPTION and routes to purchase IF I WISH TO, with perhaps some reward or special treatment for me as a fan of your brand and Page.
There are some companies out there who do this very well. A number of car brands I follow, many of which I wouldn't buy but I have an interest in, do a great job of telling me what they are doing, about new models, appearances at motor shows, dealer open days, stories of cars and their owners etc. No pushy buy buy buy stuff at all. Because they know that they are building a base of fans on Facebook, NOT necessarily customers.
Advocates are valuable too.
Different rules entirely for B2B brands, where I am unconvinced that there's likely to be significant interest amongst the Facebook crowd at this stage, just because people live their live in silos and don't want to Like their accountant while they browse wedding photos.