The dating website not only brazenly offers a service many find morally questionable – offering married people the chance to cheat "in secret" – but it has always seemed to do so with an air of glee and sleaze.

"Life is short. Have an affair" its carefree slogan beckons. Its advertising is sexist and shameless: Hillary Clinton was featured on one of their billboards, as was a plus-sized model unwittingly used to depict a "scary" (read: fat) wife you might want to cheat on. Its founder, Noel Biderman​, self-servingly claims infidelity – the kind you pay him to facilitate – "will save the modern marriage".

So it's little surprise that the news that a data breach, possibly a hack, had occurred and that the personal information of millions of customers could be released.  It was met with some amusement, even a little spite, from the general public.

It's an episode that has challenged how the public and media reacts to gross invasions of privacy when the victims are people some have little sympathy for. But it has also sharply focused attention on the growing threat of data breaches and hacks in an era when more and more of our life, even clandestine affairs, or just flirting with the idea of one, is conducted online.

The news first broke on Sunday that a previously unknown group or individual calling themselves the Impact Team was threatening to expose 37 million customer records "including profiles with all the customers' secret sexual fantasies and matching credit card transactions, real names and addresses" unless parent company Avid Life Media (ALM) took down Ashley Madison and another site it owns, Established Men.

It identified two male customers (at least 60 per cent of the sites' clientele is male) by name to prove it had bona fide access.

The company has since said it believes someone who once had lawful access to their network is responsible. The Impact Team's statement hinted as such, taunting ALM: "you thought you had never pissed anyone off."

But the team claimed its motivation was primarily indignation that customers had been sold a lie, because as the breach showed, Ashley Madison's promise of total discretion was false. There was also a strain of moral vigilantism, describing users as "cheating dirtbags", and the website's creators as people who "profit off the pain of others".

While many online clearly share that view, some have pointed out that siding with the hackers reveals  a callous attitude to a serious breach of privacy and blackmail threat.

Dan Savage, a popular US sex columnist, argued there was a double standard in the glee that met this hack and the contrasting condemnation for the media outlet Gawker, a blog lambasted for recently publishing allegations of a married businessman's attempt to hire a male escort.

"Marriage is complicated, cheating is complicated," argued Savage. "You know what's not complicated? Outing. That executive Gawker outed last week didn't deserve it, and the members of Ashley Madison being outed today don't deserve it either."

On Reddit, the hugely popular online forum, Ashley Madison users went  into meltdown this week.

"I'm a wreck. I can't concentrate at work," wrote one man. "I never even met anyone on the site. Talked to a lot of people, but nothing ever materialised and mostly because I realised that I didn't want to go through with something like that."

ALM has acknowledged the breach, which it has labelled "cyber-terrorism", and said it has now been able to "secure our sites, and close the unauthorised access points".

This latest breach of user data  adds to questions about how well companies are safeguarding our information against increasingly ubiquitous hack attacks and malicious leaks, and whether we as individuals should be handing so much of it over in the first place.

Adult Friend Finder, another hook-up website, was the also the victim of a hack recently, with the user information of millions of people, including their sexual preferences and desires, accessed and the data used to try to blackmail the company. Personal information and credit card details have also been stolen from companies including Sony, the US Postal Service, Target and JP Morgan.

Technology writer Russell Brandom argued there was plenty of data held by Ashley Madison that should have been made fully anonymous or not held in the first place, like real names and addresses.

"There's no obvious technical failure to blame for the breach … but there was a serious data management problem, and it's entirely Ashley Madison's fault," he wrote on The Verge.

So far though, the Impact Team hasn't yet released any more user information, perhaps scared off by the credible threat of legal action.

That could still change, of course, but for now, the hack's biggest impact has been highlighting these issues, while stirring fear in millions of users, who may soon find themselves bearing a modern day scarlet letter.