The problem is not just the cults but also the regular Roshei Yeshiva and Torah scholars who take a passive attitude towards highly destructive groups as long as they parade and display outer `signs of religiosity.
At least Reb Shmuel Berenbaum [the Rosh Yeshiva of the Mir in NY] was adamant not to give any open agreements in writing or otherwise to any religious organizations. His "thing" was to learn and keep Torah.
Reb Shmuel had high confidence in "learning Torah". He considered this practice as being a cure all for every kind of aliment in mind body and spirit. [That is obviously the same approach as the Gra and the Nefesh HaChaim]. [I to some degree agree with this, but I add also Physics and Metaphysics based on the Rambam who puts these two subjects into the category of the Oral Law, as you can see in הלכות תלמוד תורה in the law where he says to divide one' learning into three parts. One is Talmud. And he adds '' העניינים הנקראים פרדס הם בכלל הגמרא. And he already defined פרדס In the first four chapters of Mishne Torah.]
I also add these two subjects because as the Gra said to the degree one lacks knowledge of the seven wisdoms [Trivium and Quadrivium] to that degree he will be lacking in knowledge of the Torah, and I by experience have come to see the truth of that observation.
[One side benefit of math, I noticed, is that it tends to weed out pseudo intellectuals. That is-- there are people that think they are smart because they learned some Torah. This they assume means they are super geniuses in everything. Just a drop of math tends to put a damper onto such illusions. Math is an amazing filter. The pseudo intellectuals can get by every other filter, but not this one. This is the one thing that really separates the really talented people from the fakers that pretend to be smart because they give each other credentials.
In fact , come to think of it, why not give every person in kollel a math test? That would take them down a few notches from "We are the elite of Israel and so everyone should give us money" to "We are the most stupid and incapable in Israel and can not do anything productive and so please give us money." It does irk me that people that are really stupid can pretend to be geniuses and by that have caused infinite damage to Israel
I have been around the block a few times and so I have seen groups claiming that some practice or other will bring one ultimate salvation in this world and then next, and also seen enough counter examples to falsify all their claims. The only thing left standing in my opinion is learning Torah as the Gra held and heard from Reb Shmuel Berenbaum.
How do you have a counter examples for a claim about salvation? Mainly things that indicate otherwise. For example a claim if you come to such and such a place and do such a such a ritual you will be saved and have your whole life changed for the better and someone comes there and does that after fasting for forty days and saying the whole psalms forty days in a row and then comes and dies right then and there, I would say we have a good counter example.
It is the kind of process you us to falsify a philosophical claim. You find a plausible counter example as e.g.empiricism. Or the same way you falsify a theory in physics. You find one counter example.
And this same process works for spiritual claims.
[The main groups to avoid are those censured by the Gra for being cults. Reb Nachman I should make an exception for since he was a great tzadik and not within the category of the cherem [excommunication.] Still the groups that supposedly follow his path are problematic. It is not worth leaving a legitimate Litvak yeshiva to run after false leaders.]