It is almost a century since the Michelin brothers had the brainwave of supplementing their motorists’ guide with information about fine-dining establishments. Their star-rating system had become a mainstay of lifestyle reviews long before the Internet came along. In the digital age, this work has been comprehensively crowd-sourced: the immense success of review sites such as Yelp and Amazon has been built on the voluntary input of users. In theory, it should have been a consumer rights utopia. But product reviews are big business — and where there is lucre, there are shenanigans.

‘Astroturfing’ — the posting of fake reviews by competitors or business owners — is just one of a number of nefarious practices catalogued by Joseph Reagle in Reading the Comments. In recent years California-based Yelp has found itself the subject of several lawsuits, and a Federal Trade Commission investigation, following allegations that the site used the threat of unfavourable coverage to extort advertising revenues from hundreds of small businesses.

The nexus of publishing and advertising is, of course, perennially fraught. Witness the recent goings-on at the Daily Telegraph, whose chief political commentator resigned in February claiming the paper had compromised its coverage of the HSBC scandal for commercial reasons. Online comment manipulation is no different: strip away the algorithmic complexity and it’s the age-old story of people and businesses scrabbling for attention and influence.

Reading the Comments is not, however, a treatise on digital-era business ethics. As Reagle astutely observes, there is much more to online comment than just rating books and restaurants. Even the simple act of ‘liking’ a Facebook status — or an Instagram picture, or a Tumblr post — is a form of online comment. Regular users of social media are locked in a perpetual loop of appraisal and validation; and a growing body of research suggests this is having a detrimental impact on self-esteem and emotional wellbeing. A generation steeped in the curation of online identities is increasingly starting to think critically about its pernicious implications.

The trouble is that this narcissist aspect has been part of the internet experience from the very beginning. Some of the earliest web content to ‘go viral’ were the Hot or Not videos — in which people posted footage of themselves online and invited others to rate their attractiveness — that inspired the founders of YouTube. The fluid inter-facing of identity, approval and social status is woven into the very fabric of digital culture. It is powerfully addictive.

Whitney Phillips puts the likers and manipulators to one side and focuses exclusively on the haters. This Is Why We Can’t Have Nice Things is a fascinating study of some of the most unpleasant people on the internet — the sorts of folk who invade memorial pages for teenage suicides and post cruel, gloating messages or images of nooses for no reason other than the sheer transgressive thrill of inflicting emotional pain. Like a 19th-century anthropologist studying a remote indigenous tribe, Phillips has embedded herself among the sophomoric denizens of 4chan, the hugely popular troll forum. Her subjects, a motley collection of geeks, hackers and misanthropes, are overwhelmingly youngish males, mostly American but with a fair smattering of Brits and Aussies; they communicate in argot and their banter is often explicitly and unapologetically racist, misogynistic and homophobic. Their historic raison d’être is the pursuit of ‘lulz’ — a bastardisation of the ubiquitous ‘laugh out loud’ acronym, denoting mirthless cruel laughter.

Phillips avers that these young men are taking their lead from the US cultural mainstream. She cites the Fox News network’s sensationalist coverage of the ‘Birther’ movement — the campaign by right wing Americans to destabilise Barrack Obama’s 2008 election campaign by calling into question the authenticity of his American birth certificate — as one of a number of examples of US corporate media winking at atavistic racial chauvinism. Online trolls, she explains, are merely ‘cultural dung beetles’, revelling in society’s ordure. Indeed, though the same might be said of just about any category of hooligan at any point in history.

This community of merry pranksters has undergone a remarkable split in recent years. When the hacker collective Anonymous, which grew out of the 4chan message boards, achieved widespread visibility through its role in helping foment 2011’s huge Occupy Wall Street demonstrations, stalwart trolls took vocal exception to seeing their milieu suddenly inundated with activists hell bent on trying to make the world a better place, adulterating their nihilistic oasis with earnest talk of social justice. Cue a schism, which persists to this day, between self-styled ‘lulzfags’ — who are in it purely for the ‘lulz’ — and the idealistic newcomers, disparaged by the former as ‘causefags’ and ‘moralfags’. Alas, nothing is sacred these days.