You have a better chance if you pick up you phone, start recording and pretend to interview one of the possible candidates.
With questions like, where are you from what do you think of this rally and so on so forth...
Subtle things probably, like the way shoes are laced up, or a particular pin, or they straight up know one another.
Their handlers would immediately be in their earpieces calling out any would-be infiltrators.
Secret handshake
You could a wear an FBI hat with bullet holes through it and see who gets pissed off.
They do it different ways, sometimes they are all known to each other, others it’s an identifiable item. Agents from all over the country can board flights to somewhere, all show up independently, work a subject or place together because they all got the same duffel bag overnighted to them the night before they left. Common looking but with some unique identifier as they were all custom made the day before for this mission. Good money in government ontracting at silly prices. Watches, stripes on socks, pins…. All possible.
They'll single you out right away probably.
Better to just make a mockery of them. Wear their getup with underwear that say "Fed Fag" or somwthing like that on the waistband and let it show slightly for them to read.
I think they wear one distinctive piece of clothing that separates them from others. You'd have to be there to see them then imitate whatever they're wearing. It would be best to have an entire costume/wardrobe ready to go with everything you'd need.
They have various ways to signal to each other.... Like types of stickers on vehicles for example
Oh now (((the gateway pundit))) is in on it
They arrested an undercover at Justice For Jan 6 in that exact scenario
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