You have, no doubt, encountered this at some point. You meet someone who is completely immune to all evidence, logic, and reason opposing a position that they hold because they have managed to convince themselves that there is some conspiracy, dark force, or flaw in everyone else's mind that prevents them from admitting "the truth!" Anything that you may say contrary to their conclusions must be wrong, because you and/or your information have some fatal flaw that prevents you either from ever actually seeing the truth, or from admitting it.
You may have even committed this fallacy, but you have definitely encountered it.
I first became aware of it some years back, when I encountered the wild and woolly world of pseudo-archaeology - the land of the Graham Hancocks and the Von Dannikens. The usual charge was "the 'mainstream academics' don't want you to know about this because it would ruin their professorships and book deals!" With that line of thought, any disconfirming evidence could be brushed off as propaganda by those who wished to hide the truth with a capital "T". Of course, the problem, obviously, is that this is an inversion of reality: it is Hancock and company who stand to lose money and prestige if reality isn't what they are saying it is, I have written previously about why professional researchers have no reason to hide new revelations about the past.
It's essentially a variation on the "poisoning the well" logical fallacy: rather than engage in a discussion of points made or information provided, the person committing the fallacy simply declares that the person, group, or institution providing disconfirming information is somehow corrupt, evil, or deluded and therefore can not be trusted. It tends to be applied selectively, though. When someone from the demonized camp says something that seems to be in agreement with the views of the person committing the fallacy, then the claims of evil-doing or delusion are suspended and the qualities (professional qualifications, group membership, etc.) that had been demonized are now glorified. So, for example, when a professional archaeologist says something that is in agreement with Graham Hancock, Hancock is more than happy to trumpet the fact that such a fine, qualified, individual with excellent academic ties agrees; but when the same academic disagrees with Hancock, he became yet another cog in the "academic conspiracy" to hide the past. It's a neat way to deflect criticism
As I say, I first became aware of this when as a student, when I was discovering the various silly claims in pseudo-archaeology. In the years since, I have come to notice just how common this fallacy is.
For example: when you look into the research concerning herbal remedies, you find a very mixed bag. Some of the herbs have medicinal value, others are nothing but placebos, some have value but not for what they are typically used for, some are nothing but harmful, and the ones that do have some value all have side-effects*. However, when I have spoken with people who use herbal remedies, they are usually excited when research shows benefits for one of the remedies that they favor, but they tend to dismiss research that shows other remedies to be ineffective or harmful as well as research that reveals the side-effects of the remedies that are effective as being "propaganda from 'Big Pharma', who have a profit motive for keeping you away from natural cures!**"
Glenn Beck has made ample use of this fallacy in his forays into pseudo-archaeology and pseudo-history. Again, the claim is that "the liberal elite" are covering up the truth about the past for their own nefarious ideological ends, and it is only Glenn Beck and his friends who are brave enough to reveal the true history to us all. Any evidence presented contrary to their views is simply brushed aside as evidence that the person presenting it has either been duped by some shadowy conspiracy of "the elites" or else is an active agent of said conspiracy. Just as Hancock is the one who actually stands to lose book sales if people don't believe him, and herb producers have the same profit motive as the "big pharma" that they criticize, Beck is creating a false history that suits his own ideological ends while accusing those who disagree with him of the very thing that he is doing.
But it is not a real argument in favor of anything. It is a deflection, essentially an admission that one has no legs to stand on and therefore will simply accuse anyone who disagrees of wrong-doings. Worse, those making these sorts of claims are usually hypocrites, doing the very thing that of which they accuse their opponents. When one hears someone say "well, my opponents claim X because, and only because they are guarding their ideological interests!" you should always be wary. It's not a guarantee, but there is a fair chance that the person with whom you are speaking is guilty of precisely what they are accusing everyone else of doing.
*Simple fact of the matter - if something has an effect on your body, it's due to the fact that it's monkeying around with your body chemistry. Everything that effects us, for good or for ill, has side-effects, no matter whether the substance is grown in the garden or manufactured in a lab. If something truly has not side-effect, then it's a fair bet that it has no effect at all.
**Because, you know, the companies that manufacture and sell herbal remedies never make any profit and have absolutely no financial incentive in getting you to use their products.