Lets suspect that there is amidst us cozy campfire philosophers a mean spirited traitor of the worst kind. But he masks himslef as one of us! Who could it be?
Spy for whom?? And who exactly is “us”?
In such an endeavor I would think to begin by the process of elimination. Who is clearly NOT trying to “appear as one of us”?
After that, consider the like-mindedness of philosophies. Is the person consistently supporting a philosophy different than he declares? Which “foreign philosophy” is he supporting (who might he be reporting to?).
But of course, in an open forum, one need not participate to be a “spy”. Why would they expose themselves? It is more rational to think that rather than being a spy, they are a drone, autotomically bending conversion and thought toward their loyalty.
Very many organizations have been involved in that very thing. On the internet, it is easy. Horus from Egyptian days (and since) is all about watching. So you have the Jews, the Secularists, Illuminati, Catholics, Jesuits, Homeland Security, CIA, and well,… just about thousand others. Obfuscation is the very foundation of spying and manipulation.
The more significant question might be, “What could you do about it?” 
There is an old masonic saying which says the more you resist something the more power you give to it.
Said the spider to the fly.
…emm… or was that the Borg? {{resistance is futile}}
Or Horselover Fat’s Chinese finger trap. Ooh. ILP as the finger trap of a Borg entity. It’s the island of No Escape for anyone who has killed their commanding officer, namely God. Our friend Friedrich Nietzsche lurks here as its resident ghost, and those inclined to ancestor worship roam its residence halls searching through the rooms of dead philosophers who believed in God and managed to avoid the trap, only to find No Exit and the Good Book on each bureau – no, not Gideon’s Bible but Retching with Nothingness or Waiting for Hairy Altos (Jean Paul Beckett at his finest), just a little light reading to help while away life in the horror vacui filled by the cobwebs of SF and spy movies. 
me
Could be me as well…
not me. 
Lol. If everyone here is a spy, then they’ll start a thread called: who on this forum is not a spy?
Well, whoever the spy is, they must have really pissed off their boss to get this assignment.
That was my thought. Who the fuck would want THAT job? 
I don’t understand the OP.
On a side note,
Perhaps a social version of Newton’s ‘‘equal and opposite reaction’’, concerning the ability of an entity to rework the energy at whim.
I used to be a spy, but then i got burned
Sam and Fi got your back, though. 
The spy film genre deals with the subject of fictional espionage, either in a realistic way such as the adaptations of John Le Carré or as a basis for fantasy such as James Bond. Many novels in the spy fiction genre have been adapted as films.
horus is a pretty shitty god if all he does is watch
The first premesis for a spy, is to retrieve information …what information would be so valuable for someone to spy? What interest should there be in spying in an open forum where most posts aren’t even with a slight scientific height …but nonsen and babble?
The only spies I know of are google and other such search bots which scans things.
Befriend you, then treat your sorry ass like shit. All types of spies these days, ya know.
Some of the most mean spirited folks on the planet are capable of such wonderful acts of kindness all in the name of Zandali. - Just saying 
Please provide som examples of such most extraordinary claim.