Do you accept "friend" requests from everyone who asks for it through your Facebook and LinkedIn account? I do. Even people I've met just once at a conference. But lately I've started to think it may not be a good idea. Consider the case of Bernie Madoff, the $50 billion dollar ponzi scheme mastermind. There were probably, dozens, if not hundreds of investment professionals that worked in the industry who now have to work backward to separate themselves from Madoff's firm. They took photos with him at events and probably sent business his way on more than one occasion. And all thought they knew him as a friend. Certainly they thought they knew his reputation better than a person they met one time at a conference.
Some people may argue that they way they use social networks is to connect with people - regardless of how thin those connections may be. But keep in mind that there is no degree of friend designation on sites like Facebook or LinkedIn. That person I met once at a conference is the same type of "friend" as my college roommate whom I've known for 20 years on Facebook. It would be interesting to be able to categorize people as "friends" or "acquaintances" for people we don't know very well.
I consider "friends" to be people I would trust to babysit my daughter. Yet I have over 600 "friends" on Facebook that I probably wouldn't even recognize if they walked into my office at this very moment. And yet I "friend" them without a second thought - connecting them, if in just a small way, to my own online reputation. Heaven forbid they should do something awful, I might have some explaining to do when asked why they are my friend on Facebook.
Offline, you can tell a lot about a person by the company they keep. Why should online be any different?