Stephen King wrote the novel Misery that later became a movie of the same name. Although I've not read it, Wikipedia tells me it's a story about a women who rescues an author after he crashes his car in the snow. She recognises him as her favourite author of a series she's obsessed with. Locked in by the snow, she takes him to her home and nurses him for months. However she discovers a manuscript of his latest novel and doesn't like it. Her series is ruined and it eventually leads her to cut off his foot, holds him captive and forces him to rewrite the ending.
I think social media, particularly community managers, are increasingly going to have the same problem.
Social media is great for building a community around your brand, or bringing together an already established one. What you can then do with this group of evangelists is limited only by your creativity.
But by bringing together this group of hardcore fans, you also bring in the fans that are a little too hardcore; the fans whose obsession with your brand becomes harmful. They don't quite fit the mold of your perfect target market, where their social awkwardness is not limited on platforms of such an impersonal nature. Their constant activity becomes spam and a slight wrongdoing in their eyes creates an unwarranted response. These obsessed lovers become haters.
I have a friend who does promo work, usually giving away free samples. I found it amusing when she told me she was only allowed to approach consumers who were in the target market, but never to turn down anyone when they approached her, no matter who they were. Many of those who approached her would not reflect positively on the brand. But she dealt with them by keeping them happy, allowing them to move on.
But with social media these people don't have to leave. These crazies can continue to interact with the normals and when you create a branded community, they think they're being encouraged to do so.
And dealing with these people can be difficult. Particularly if you like your feet....