I was down in the NYC subway waiting for my train. This guy is taking pics of the tracks, pics of the tunnels, pics of the platform,etc. and looking around. I followed him onto the train and when I got off I told the conductor about him. That was that. If I saw someone spritzing something around where I was sitting, i would have said, what the eff are you doing? LOL
I think, that for the sake of our national security and our very own lives, we all need to be individual sleuths, and report suspicious things. I think we should all have the phone number of the local FBI office and non-emergency police programmed into our cellphones, and call them immediately, when witnessing something strange.
I vaguely remember they caught some terrorists, because someone reported a moving van parked in an unusal place, and insisted that the police check it out -- they found videos of US landmarks, focusing on aspects that no tourists would photograph. I think it was a year or two ago.
Also remember actor James Wood observed and reported when the terrorists were doing a dry run PRIOR to 9-11-01 attack, but at that time, they didn't take him seriously, because the terrorists weren't "doing anything", merely acting suspicious, and not in a way normal passenger would act. If they had, they may have uncovered the whole plot. AFTER 9-11-01, he identified I think two of the terrorists of the 19, who were on his flight in July 2001.
Sure, many of those things could be false alarms, but rather report 100 false alarm, than miss one real event, that could prevent the next attack.