Mass US spying can't catch bad guys because it's not looking for bad guys. Axelrod said Obama's first thought about Boston Marathon bomber was it was a 'tax day' protester. Bloomberg's first thought about the 2010 Times Square bomber was it was an American who disliked the Health care bill

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Translation: Both Obama and Bloomberg's first impressions were that Tea Partiers committed terrorist bombings:

4/16/13, "Axelrod: Obama Thinks Boston Bombings Could Be Related to 'Tax Day'," Weekly Standard, Daniel Halper

"In explaining why President Obama didn't call the Boston bombings a "terrorist attack," former adviser David Axelrod said, "I'm sure what was going through the president's mind is -- we really don't know who did this -- it was tax day" (MSNBC video)....

"The word has taken on a different meaning since 9/11," Axelrod said of the phrase "terrorist attack."
"You use those words and it means something very specific in people's mind. And I'm sure what was going through the president's mind is -- we really don't know who did this -- it was tax day. Was it someone who was pro--you know, you just don't know. And so I think his attitude is, let's not put any inference into this, let's just make clear that we're going to get the people responsible."

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The left thinks alike:

In 2010 NYC Mayor Bloomberg had a similar first impression about the Times Square bomber who also turned out to be a Muslim:

5/3/2010, "Bloomberg: NYC Bomb Suspect Someone With A "Political Agenda," Real Clear Politics

"“If I had to guess, twenty five cents, this would be exactly that,” Bloomberg said. “Homegrown maybe a mentally deranged person or someone with a political agenda that doesn’t like the health care bill or something. It could be anything.”"