Do you mean that social networking sites promote useless information? I think so. Facebook pages don't exactly have any educational value...it's 500 million pages of what people are doing on the weekend.
There is an upside, though-it has a habit of spreading the word about events, charities and causes. That's pretty much the only useful information in all of Facebook, though. I could say the same about other sites, like Twitter and Myspace.
Now Funadvice-this site is actually full of useful information :)