Now that everyone is a publisher of content via Facebook, Twitter and Pinterest we all have mediums to express ourselves and our purposes, through the content we curate. Brands interested in having their followers re-share the content they post need to think in terms of whether or not re-sharing it will allow their followers to express their personal purpose.
I think most people are realizing that what they share says something about themselves that other people, mostly strangers, will use to judge them. Liking something on Facebook to get a coupon says something that that person might not want to be said about themselves. People curate content for their own personal brand just like big brands do and are just as concerned with being “off-brand”.
I think self expression through curation is one more important filter to consider in deciding what a brand should post.