>> It just seems like I'm a) giving fb more information about me and b) inviting gatorade to try and sell me things. Am I wrong or is becoming a fan of a brand just all bad for the user and all good for fb/the brand?

This assumes that giving Facebook information to deliver ads for things you actually want is a bad thing, a position I disagree with. No matter how hard I try, I will be advertised to. I'd prefer to get ads for things I might actually want than a return to the lowest common denominator ads of the past (which tend to be things like diploma mills, insurance, or payday loans).