Wow, no wonder government agencies salivate at the idea of being able to monitor the whole Interwebs.
I know they now have orders of magnitude more data to process but still... that manual process must have been expensive and boring as hell.
I guess as an agent you would need to convince yourself that this was actually a very important task of defending your country or something. Otherwise I can imagine going crazy just doing this stuff for nothing...
Edit:
Another quote I found amusing:
"The friendlier one eventually described how much it had cost to investigate another recent case where a person was reported to have pulled down an American flag and stepped on it. Only after the investigation was well under way did they learn that the perpetrator of this nefarious act was only four years old."