Of course, we all grew up hearing the same things told of the Soviet government: it was lying about everything to us... and especially to their citizens about the US.
I think it's safe to say all governments lie about a lot of things, both internationally and domestically.
And here's some debunking of a few or the more persistent Marathon bombing rumors and conspiracies, including the legs-missing guy picture: http://www.snopes.com/politics/consp...oston.asp#vogt
Of course, true conspiracy-minded folks won't let that deter them, and choose not to believe sites like Snopes, calling it a tool for the shady powers-that-be...
But, I also know that most of the "fake bombing" theory folks also haven't walked around Copley Square and seen the damage, or happen to know folks who were standing a block removed from ground-zero when it all went down and saw it live and in person with their own eyes. I have, and I do.