Decreased Productivity
While many businesses use social networking sites to find and communicate with clients, the sites can also prove a great distraction to employees who may show more interest in what their friends are posting than in their work tasks. Wired.com posted two studies which demonstrated damage to productivity caused by social networking: Nucleus Research reported that Facebook shaves 1.5% off office productivity while Morse claimed that British companies lost 2.2 billion a year to the social phenomenon. New technology products have become available that allow social networks to be blocked, but their effectiveness remains spotty.
Privacy
Social networking sites encourage people to be more public about their personal lives. Because intimate details of our lives can be posted so easily, users are prone to bypass the filters they might normally employ when talking about their private lives. What's more, the things they post remain available indefinitely. While at one moment a photo of friends doing shots at a party may seem harmless, the image may appear less attractive in the context of an employer doing a background check. While most sites allow their users to control who sees the things they've posted, such limitations are often forgotten, can be difficult to control or don't work as well as advertised.