When people enjoy a book, they probably believe that it comprises mostly true statements. They agree with the main arguments, share the author's point of view, and only rarely disagree with something he says. But if a book makes thousands of claims, it's impossible for an author to get more than 90% of them right. The book just has to be littered with a mix of truths and falsehoods. When people say untrue things, it's usually because they used sloppy wording to say a thing that actually is true.
Case in point, the above paragraph was generally correct but it contained no true sentences. (Look back. After every sentence, ask yourself if the statement is true or not. I wrote each one to be at least somewhat questionable.)
A really bad writer says almost no true things. I Google Scholared "post-structuralism" and this was the first paragraph of the first available essay that popped up:
"For many contemporary feminist theorists, the concept of woman is a problem. It is a problem of primary significance because the concept of woman is the central concept for feminist theory and yet it is a concept that is impossible to formulate precisely for feminists. It is the central concept for feminists because the concept and category of woman is the necessary point of departure for any feminist theory and feminist politics, predicated as these are on the transformation of women's lived experience in contemporary culture and the reevaluation of social theory and practice from women's point of view. But as a concept it is radically problematic precisely for feminists because it is crowded with the overdeterminations of male supremacy, invoking in every formulation the limit, contrasting Other, or mediated self-reflection of a culture built on the control of females. In attempting to speak for women, feminism often seems to presuppose that it knows what women truly are, but such an assumption is foolhardy given that every source of knowledge about women has been contaminated with misogyny and sexism. No matter where we turn-to historical documents, philosophical constructions, social scientific statistics, introspection, or daily practices-the mediation of female bodies into constructions of woman is dominated by misogynist discourse. For feminists, who must transcend this discourse, it appears we have nowhere to turn."
I underlined every second sentence to make it more apparent where each sentence begins and ends.
The paragraph begins with a couple of sentences that may well be true, but it soon turns into a bunch of claims and implications that are either clearly false or just plain incoherent. But criticizing post-structuralist theory is too easy. Let's take another example, one that is less obviously nonsense.
Take this paragraph from the opening chapter of Kalle Lasn's Culture Jam:
"A free, authentic life is no longer possible in America today. We are being manipulated in the most insidious way. Our emotions, personalities and core values are under siege from media and cultural forces too complex to decode. A continuous product message has woven itself into designer lives--sleep, eat, sit in car, work, shop, watch TV, sleep again. I doubt there's more than a handful of free, spontaneous minutes anywhere in that cycle. We ourselves have been branded. The human spirit of prideful contrariness and fierce independence has been oddly tamed. We have evolved into a smile-button culture. We wear the trendiest fashions, drive the best cars industry can produce an project an image of incredible affluence--cool people living life to the hilt. But behind that happy mask is a face so ugly it invariably shocks the hell out of my friends from developing countries who come to visit, expecting the giddy Americana depicted on TV and finding instead a horror show of disconnection and anomie."
This is a typical paragraph in the book. Although if one were to steelman this paragraph, it would be possible to identify some good observations and arguments, it's shocking how difficult it is to simply find a true sentence. In the above paragraph, barely any sentence is actually true. Despite it arguably being more or less on the mark regarding the superficiality of American culture, almost no sentence in the paragraph says true things.
When reading or writing, a good habit is to go sentence by sentence, asking yourself whether the sentence in the hot seat is true or not. This is a way to improve your ability to reason clearly, notice bad arguments, and clean up your own writing.