...when there just might be video available that completely contradicts your story.
Yesterday, a blogger posted a lengthy story, TSA agents took my son, claiming that her son had been taken from her during a secondary screening at the Atlanta airport. She also posted a link to her post on Twitter and asked people to retweet it. Many did, most expressing outrage at TSA's insensitive (and against their stated policy) behavior.
Some hours later, TSA responded to the complaint on their own blog. They also included video of the situation taken by the airport's security cameras that showed a very different situation from what the woman had reported, thus unleashing an entirely different kind of outpouring. (I waited to write this post in case she had some explanation for the discrepancies, but her response does nothing to support her original accusations.)
There's no question that social media has proven that it can be a great tool for spreading the word about truly egregious behavior, from poor customer service to brutal government oppression. But I think this incident proves that it's equally as great a tool for getting hoisted by your own petard.