Do you suspect there are any infiltrators or government agents who go to your chapel and pretend to be trads but are really spies? Some people at my chapel suspect one of our servers of being a FED. 

FEDS?   How about converso Jєωs at your chapel?   How many do you have?

It seems almost every chapel has it's little group of Jєωs.

What is the chance they are fake converts, i.e., Marranos?

If they are sympathetic to Israel, they are fake and need to be closely watched. 

Keeping aware of what your chapel Jєωs are doing is a universal Catholic practice.

With so many changes in the SSPX, I would not doubt if some at the top are actually infiltrators. 
This neo-SSPX should be avoided.

I am glad that this issued is posted.  Our first encounter with infiltrators was in Edinburgh, Scotland.  There for 3 weeks visiting and each week in July saw trouble in SSPX. (July 2019).  Then spoke with people from Malaysia and they too experienced what we did. They said the word "infiltrators", then I agreed, yes!

This should not be surprising, but the parishes need to keep note of being watchful, aware, and give them no attention.  

What we noticed was women demanding not to wear head coverings, wearing slacks.  Then Priest having a homily on Christ present in both species. Then after distributing Eucharist, 2 people come to the communion rail, with white gloves and both receive wine.  (We know that a crumb is all needed to have Christ).  The next Sunday, Benediction after Mass.  After Eucharist, half the people left and never came back! Very sad, but that was SSPX in Scotland. We went as observers and we kept Our Sunday Holy.

I know of a Traditional Church with independent priest being watched by New Order to report back to bishop of dioceses. That priest knew of it.  1986.

I do think it should be an issue to speak of and how to handle it.  Ushers are very important to watch and to maintain dress codes and such.  Once they start, if you don't stop, they will continue.  You can start off "friendly" and how is that defined?  But you must nip things in a bud.  We know that Christ is Truly Present, then be sure to have greeters, and that they do their job.

What are "and FEDS"?

A federal agent pretending to be a trad? It would take years of training to learn not only the doctrines that we believe, but to memorize the prayers and learn all the other things that we pick up over the course of a lifetime, that would be necessary to make a convincing act of being a trad.
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Do you really think spooks take classes at Langley on which saint to pray to to help your cat get better, or where the Council of Trent was held, or the story of the 40 Holy Martyrs? Or how much of an indulgence you get for saying the rosary? Any trad's head is crammed with those and similar facts, which as I said could only take a lifetime to acquire.
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The idea seems borderline impossible, so unless the person you suspect of this is wearing a discreet earpiece and seems to be receiving verbal cues from it when he's talking to you, I wouldn't worry about it.

Nah. The feds hang out on innernet forums. For some reason they usually use hairy animals as avatars.

I can tell you that a few weeks a go, the more obvious Fed-Neocaths were shilling for Bruce Kardashian. 

They also tend to over-focus on issues like abortion, while going on the attack against "racists" and other bogeymen counting on the spirit of self-righteousness of a few other to join in. 

Do you suspect there are any infiltrators or government agents who go to your chapel and pretend to be trads but are really spies? Some people at my chapel suspect one of our servers of being a FED.

Feds don't usually get directly involved unless the group becomes too large. What they do is look for people with higher aspirations but who have stronger narcissistic tendencies and are unfamiliar with cosmopolitanism and realpolitik. On the old ABLF forum, Tele and PereJoseph discussed this about Bishop Fellay.