The article by Eliane Glaser here raises the question of whether the concept of false consciousness is a useful one. I don't find Glaser's article illuminating, but the question is of interest nonetheless, and I shall put down a few stray and incomplete thoughts about it.
(1) There are non-problematic instances of the idea of false consciousness, arising when someone can persuasively be said not to know their own interests. The simplest example would be from medicine. A person who is diabetic but isn't aware that he is, and whose aims in life include remaining in reasonably good health so far as possible, will not know that it is in his interests to alter aspects of his lifestyle, especially his diet. Medical examination - however triggered - might then reveal his condition to others, to doctors, and if that happens the doctors may know, at least temporarily, what the guy needs better than he does. To say that his partiality for large helpings of high-sugar foods is a product of false consciouness would not be inappropriate in such circumstances.
(2) A non-medical example might be of someone with ambitious projects who never seems to get anywhere with any of them, and is advised by a friend with whom she shares a flat that she could fare better if she were better organized. The friend may be able to see what she herself has failed to, that she is using some of her time badly - and so forth. Listening to the advice, and changing her ways, she finds that things begin to move along for her much better than before.
(3) On the basis of these simple examples, I would say that to claim to know someone else's interest better than they do is not in itself either arrogant or sinister, provided that the claim is spelt out with care and supporting evidence and reasoning, and that the person concerned is given a proper opportunity to digest what is said and to respond, whether receptively or not.
(4) The idea of false consciousness and of A's knowing better than B what is in B's best interest, becomes sinister and worse than arrogant when it threatens B's autonomy; when in the name of A's superior knowledge, something is to be imposed on B, supposedly in pursuit of B's own interests.
(5) Suppose that B is a longtime smoker who intends to continue smoking; but not because he is ignorant of the harmful consequences for his health that his smoking could cause; rather, knowing them as well as anyone and yet choosing to incur the risk. It is false to claim of B in these circumstances that forcing him to give up smoking would be a kind act based on knowing his interests better than he does. By choosing to smoke in full knowledge of the possible consequences, he has adopted an identity or persona such that remaining healthy isn't one of his priorities. We have to construe his interests in the light of the kind of person he wants to be (and this evidently doesn't include wanting optimal health), rather than the kind of person others want him to be.
(6) In a political context the idea of false consciousness is now rightly held in suspicion because sometimes people's quite genuine and harmless wants are represented by would-be knower-betters as delusional and the product of not really being aware of what is good for them.
(7) A common example of 6 that I've discussed more than once on this blog is when commentators who have all the time in the world for people taking an interest in [hushed tone]CULTURE[/hushed tone] disparage the enthusiasm of millions of others for following spectator sports, as though they - the commentators - had some serious grounds on which to judge that this was a bad thing to do and damaging in particular to the lives of the enthusiasts.
(8) The idea of false consciousness has especially acquired a bad name because of the way it has been used politically in defence of authoritarian politics – to impose solutions on people without their democratic consent and supposedly on behalf of their alleged long-term interests (which are said to be known by the body claiming this authority for what it does).
(9) A particular danger here is that the long-term interest being invoked is often not the interest of these living individuals right now, but rather the putative interest of their social group or class. However, if the gain envisaged for them is very long-term, then the sacrifices demanded in the present may not be matched by any effective return to the aforesaid living individuals, and so not in their interests at all.
(10) Glaser alludes in passing to the formula of speaking truth to power. The criticism of unjust power is a never-ending task. However, the presumption of those who deploy this formula is that they know what the truth is; and they don't always.