... so we are playing spot the spook now?
I thought there were laws that public officials acting in official capacity have to make themselves known when asked ... or is it just a crypto-police state, not a real one?
The idea that an officer or other public official must identify themself if asked is a myth propagated by undercover cops.
At least here in the U.S. cops are allowed to lie to you. That's pretty well known.
As far as "spot the fed", a few years ago at PorcFest there was a guy that just didn't seem to fit in and a few of the folks decided he must be a fed. He got followed around and it seemed to me to be blown out of proportion. The next year there were people walking around with t-shirts that said "I'm a fed" on the front and "Don't you wish it was that easy?" on the back.
One friend of mine suggested that if they really wanted to infiltrate a group like that (largely male and geeky) the best thing to do would be to send in a young female.