More than one-third (34%) of Americans are "tuning out" social networking sites, with 39 percent doing so because of rude behavior, according to a new survey by Weber Shandwick and KRC Research. "We prefer to communicate through social networks the same way we do in everyday social settings. We tend to congregate around shared interests. We want to know who we're talking to. And if there is a difference of opinion, we expect respectful dialogue. If not we tune out,