At the risk of being called a troglodyte, a cretin, a flat-earther or a red-state Senator, I must herein admit that I don't understand the concept of "Liking" something on Facebook. Not the value it delivers to brands, but why I would announce to the world that I like this brand or that.
I understand most people walk around "in public" (as my mother would hiss) festooned with logos, but perhaps I am inured to that banality--it's been around longer.
My relationship with brands is pretty simple and will remain that way. There's an elementary value exchange. I spend money on them if I like what they offer me. I may even talk about them if they do something fabulous. In other words, I'm mostly quid pro quo with brands. Treat me well, I'll keep buying you. That's the deal.
Liking something seems like a PDI. A public display of insecurity or maybe vacuity. I am not a person in my own right, it says to me, I am only a reflection of the brands I like.