It might indeed be the case that many "negative" reviews of fiction are glib and opportunistic exercises in what has come to be called snark. Such reviews make little real effort to adequately describe the ambitions and strategies of the book under review, or to assess the book's success or relative failure to fulfill these ambitions with any degree of specificity. If this sort of review were to disappear, neither literature nor literary criticism would register the loss.
But to dismiss all critical evaluation that reaches unfavorable conclusions as illegitimate, somehow an affront to the "community" of writers and readers who value books at a time when reading seems endangered, is not just irrational but in fact a greater danger to sustaining a serious literary culture than indiscriminate snark would ever be. That some reviews elevate shallow and superficial pronouncements over considered judgment does not mean negative reviews that are carefully considered should be equally rejected. Moreover, writers themselves should welcome the latter sort of review, since it signifies the work has been taken seriously and given close attention. This seems to me an infinitely preferable response than empty praise, which, in the absence of the more rigorous standards implied by the possibility of a negative judgment, is all that reflexive approval is destined to become.
I wouldn't necessarily use the word "smarm" to identify this kind of praise, although anyone who writes book reviews simply to uncritically celebrate otherwise mediocre writers because all writers need "support" is hard to take seriously. Especially when the reviewer is him/herself also primarily a fiction writer, readers are well-justified to think that such reviews are a form of self-protection at the least, but even when they are sincerely intended, more often than not the lack of real critical engagement with the book under review undermines credibility. Synopsis substitutes for analysis, and judgment is replaced with rhetorical flash and vacuous accolades. Indeed, this sort of rah-rah reviewing is so common, so much dominates the discourse of book reviewing at the moment, that it's always surprising to me when someone suggests there are too many negative reviews around in the first place.
The advice often given to reviewers and critics who might have something actually critical to say about a book or a writer is to just say nothing instead, to let one's silence stand as sufficient commentary. In long-form criticism, this makes some sense; extended consideration of the flaws in a particular work or a writer's body of work is not usually as worthwhile a use of critical space as the explication of the most accomplished works and admired writers. (Although dissenting evaluations of established writers that question their critical standing certainly have their place.) However, contemporaneous book reviews serve a different purpose. The best reviews do not facilitate "consumer choice" or "cultural discussion" (although some reviews might inadvertently do these things) but take on the responsibility of providing an initial critical reaction to books that presumably seek an audience not just among those who happen to read this week's newspaper, and not just among readers this month or this year, but also future readers for whom the book's literary merit has become the most important consideration, not its purely occasional interest as a "new book" or as an artifact arising from its circumstances of its publication (the review's circumstances of publication as well). In some cases, those reviews provide the only available critical guidance to such readers, but even if additional, more extended criticism has subsequently appeared, often the presuppositions at work were introduced by the initial responses to the book or writer found in reviews.
This was certainly my experience as a fledgling scholar of contemporary literature, when I was trying to round up the critical responses to writers in whose work I had an interest. Of course, most contemporary fiction has yet to accumulate the kind of formal criticism associated with more canonical literature, but I would always look first at the reviews, and usually found they had in one way or another (in rendering both positive and negative judgments) established the context in which the writer's work continued to be discussed, the most thoughtful and conscientious reviews often enough still providing valuable insights into that work. Had I been surveying reviews motivated by the perceived need to reinforce a literary "community" against attack rather than to reinforce literature itself through honest and detailed literary criticism, even in the modest form of the book review, I would most likely have found little of value and concluded that such a "literary" culture doesn't really take literature very seriously.
Certainly no writer welcomes an unfavorable evaluation of his/her work. It's another thing altogether, however, to extend one's dissatisfaction with this sort of critical scrutiny to a general proscription of negative criticism in the name of fellow-feeling for one's putative colleagues. Not only does this reduce the creation of literary art to an exercise in group solidarity, but it's practically an invitation to writers encouraging them to do shoddy work. Since whatever I might write is going to be praised simply because I wrote it (lest I get discouraged), there's no particular reason for me to artistically challenge either myself or my potential readers. Even if I have mustered up some ambition and taken risks, if the result is met with the same bland acceptance as all the less adventurous books, what motivation do I have to maintain my ambition? And if it is met with the silence that is supposed to be an adequate sign of disapproval, what reason would I have to consider this as anything other than cowardly?
The impatience with which many writers (and some critics) regard "negative" reviews is in part a natural enough response, reflecting the tense relationship between artists and their critics that has probably always existed. On the other hand, it seems to me that such tension has become particularly acute in our time because of two simultaneous and seemingly contradictory phenomena: There are more published and aspiring-to-be published writers than ever before, and the audience for serious fiction (and poetry) continues to diminish. In these circumstances, negative reviews threaten to undermine the "community" that has come to substitute for the cultural recognition poets and novelists have lost and might deprive writers of whatever small chance they have of gaining readers among what remains of a general reading audience.
Defenders of negative reviews often justify them as providing a service to readers, who will be cautioned against spending their time with an inferior book. Even those who don't think reviews are primarily a form of consumer guidance (and thus a function of capitalism more than literature) nevertheless generally contend that the evaluative role of criticism should take precedence, helping readers come to a conclusion about a given work's merit. If this is done by offering evidence and cogent analysis, it is a perfectly valid exercise, although it would seem that the occasions for performing it should be limited: What's the point of subjecting a book by an early-career writer to harsh critical treatment when it's not likely to attract much of an audience anyway and can safely be left to its fated lack of attention as an ultimate verdict? Why take up too much review space and critical effort with bad books when what's really needed is for the good but neglected books to be discovered?
After all, in the long run lengthier critical commentary isn't going to be afforded to truly inferior work. Literary criticism of a more extended sort almost always centers on books that have continued to resonate, whose success is no longer at issue. Few serious critics--and not just academic critics--are going to devote these opportunities for more thorough critical reading to largely superfluous evaluation. Despite the widespread impression of critics as prescriptive taskmasters, literary hanging judges, evaluation is not the most essential task taken up by the literary critic. At their best, critics are not judges, but more like witnesses offering an account of the reading experience that has a tentative authority that comes from close and conscientious reading allied with a grasp of context--literary, cultural, historical. A critic of this kind describes, makes connections, explicates, albeit as the means to the discovery of value, a discovery the critic hopes the reader will share.
If criticism is not the act of rendering a critical verdict on a literary work, neither is it any kind of evaluation of the author of the work, a divining of the author's character or moral standing from his/her "presence" in the text. Thus a negative review is not an attempt to find fault with the writer but to point out flaws in the work through identifiable standards. (If the standards can't be identified then the review itself is fatally flawed and can't be taken seriously, anyway.) Likewise, a positive review is not an affirmation of the writer, but the qualities of the book at hand that make it artistically successful. Quite likely most writers would not take such offense at negative reviews if they didn't implicitly believe that a positive review is not just an expression of approval of a particular book they've written but also approval of their decision to be a writer, an acknowledgment of their inherent talent.
In my view, most of the debate about positive and negative reviews is misguided not only because it oversimplifies but because it proceeds according to mistaken assumptions about the objective of reviews, and of criticism in general. Reviews should not be written as a kindness to either readers or writers but as a contribution to the continued relevance and vitality of literature. While many reviews may be no more than a transitory register of unreflective opinion or superficial pronouncement (at times no more than perfunctory plot summary), others offer genuine insight into the immediate context and the aesthetic effect of the book under review, and the very best also help maintain the continuity of literature by declining to write about a new book as if it has arrived shorn of all connection to the writer's other work and to important literary history. Collectively, reviews provide the first layer of commentary on a literary work, which can be very influential in stimulating subsequent critical consideration of that work.
A reviewer can't be sure, of course, that the work being reviewed will receive subsequent critical attention. The presumption probably should be that it won't. However, the reviewer should also presume that a book presenting itself as a serious literary work deserves to be regarded as such, but also needs to be honestly assessed when it falls short of its ambition. Ultimately both readers and writers can only benefit from this kind of effort when carried out in good faith, even if it is not directly made on behalf of the well-being or convenience of either.