On the popular website Reddit, where users submit and share content, a member of a forum called "creepshots" was handing out advice last week. His subject? How to photograph women surreptitiously. "Don't be nervous," he wrote. "If you are, you'll stand out. Don't hover too much, get your shot and move on if you can ... You'll look less like a creep if you have photos of things other than just hot chicks' asses."

He offered this advice in the comment stream attached to a gallery of photos of women snapped unawares at airports. Those images joined hundreds posted by group members of women waiting for trains, packing groceries, standing on escalators; the camera homing in on their bottom, crotch or breasts. And they joined thousands more on creep websites as a whole, a large, thriving online subculture. The point is to catch women unawares, lay claim to something off-limits, then share it around for bragging rights and comment.

Erin Gloria Ryan, a writer for popular women's website Jezebel.com, was alerted to the forum by concerned Reddit users who are trying to get it closed, partly because some of the pictures appear to have been taken in schools. The content on the creepshot forum isn't pornography, says Ryan, "but it is using people's images in ways they definitely wouldn't want authorised". For group members, she says, it seems to be precisely women's lack of consent – the violation of their privacy and agency – that is appealing.

The issue of women's pictures being taken and shared without their consent has been in the spotlight for more than a week now because of the furore around topless images of the Duchess of Cambridge. I suspect the most arresting photograph of the scandal will actually prove to be the one that shows where the photographer was apparently standing. An 'x' marks a spot on a public road, so far from the chateau where the couple were staying that you can barely make out the building itself. The perspective makes any argument against the right to privacy seem laughable, yet they continue. The editor-in-chief of Denmark's Se og Hør magazine, which published a 16-page supplement of the photos, has implied Kate must accept some responsibility for "willingly revealing her breasts towards a public road".

The story prompts questions about why there is such a market, and therefore audience, for these pictures. As others have pointed out, it is not as though there is any dearth of bare breasts, consensually exposed and shared, on the internet. The answer involves a familiar combination of desire and humiliation. There is an interest in seeing not just any breasts, but all breasts, a sense that female bodies are public property, fair game – to be claimed, admired and mocked.

Paparazzi culture has been a problem for decades, but it has taken on an especially sinister, sexualised hue in recent years. In 2008, for instance, a photo agency announced that Britney Spears definitely wasn't pregnant – by posting pictures of her in period-stained knickers. Emma Watson has said that on her 18th birthday she realised that "overnight I'd become fair game ... One photographer lay down on the floor to get a shot up my skirt. The night it was legal for them to do it, they did it. I woke up the next day and felt completely violated." At the Leveson inquiry, towards the end of 2011, Sienna Miller said that for years she was "relentlessly pursued by 10 to 15 men, almost daily ... spat at, verbally abused ... I would often find myself, at the age of 21, at midnight, running down a dark street on my own with 10 men chasing me".

While we associate this experience specifically with celebrities, we arguably all live in a paparazzi culture now. Cameras are ubiquitous, as is the technology to share and publicise pictures instantly. The throb of surveillance plays out in different ways. On the more benign side are the mild nerves many people feel when an email pops up to tell them they have been tagged in a Facebook photo, an image that could be from any moment in their life – recent or historical – now public, and open for comments.

But it also plays out in more insidious ways. This includes the creepshot websites, and others where people collect images of ordinary women they have culled from around the internet. Julia Gray, co-founder of anti-street harassment group Hollaback London, says she was horrified when a picture of her ended up in one of these groups, an image of her at her best friend's birthday party. "We were really drunk, I fell over, and my friend took a picture that happened to capture my boobs down my shirt." When she saw it in her friend's Flickr album online, she was completely relaxed about it; in that setting it was just an innocent, funny image. But then it was appropriated, "and in the context of all the other pictures – upskirt shots and down-top shots – it became incredibly creepy. All of a sudden it was this weird, voyeuristic thing, and I felt really preyed upon."

Then there is the evidence that young women are being coerced into taking suggestive pictures by their male peers, badgered in a way that is distinctly paparazzi-like. Teenagers today have grown up in an environment filled with both paparazzi pictures and images of ordinary women with their tops off. We live in the land built by gossip and lads' magazines over the past decade. Heat magazine ran its Circle of Shame feature for years, encouraging young women to look at their female peers, deride them for ugliness, and simultaneously police their own appearance. Nuts magazine went into nightclubs and asked women to flash for them. Zoo magazine asked readers, "What kind of tits do you want for YOUR girlfriend?" in a 2005 competition that offered £4,000 worth of surgery in return for pictures of readers' girlfriend's breasts.

This has been the formative environment for today's teenagers, and in a small-scale but fascinating NSPCC study published this year, researchers spoke to 35 students at two London schools, and found "peer surveillance and recording was normalised to the extent that many young people felt they had few friends they really 'trusted'".

A girl in her second year at secondary school whom the researchers spoke to reported that the demand "Can I have a picture of your tits?" occurred daily. If boys managed to get these photos, they immediately became a form of currency for them, and potential humiliation for the girls. Male interviewees spoke about posting these pictures to "exposure sites" on Facebook, profiles set up especially for this purpose.

Allyson Pereira, an anti-bullying advocate from New Jersey, has had that experience first-hand. Now in her 20s, she was 16 when her ex-boyfriend – the first boy she had dated – said he would get back together with her if she sent him a topless picture. She did, and he immediately "sent it to everybody in his contact list," she says, "and it just went viral". She found out when everyone started laughing at her, and calling her a whore. Her mother initially said they would have to move, former friends called her disgusting and teachers made jokes about it. Six months later, Pereira felt so lonely that she attempted suicide. Having planned to become a teacher herself, she abandoned the ambition, because: "I would have had to explain to every single [employer] about my past, because you never know when a picture like that is going to resurface." She didn't go to university, because she felt too vulnerable. The photo is still out there, she's sure, and although her anti-bullying work gives her pride, feels her life will always be tainted. "I don't like public places," she says, "I'm still bullied sometimes now if I go out. I have people who call me a whore."

In recent years a genre of websites dedicated to sharing humiliating pictures of women – and occasionally men – has cropped up, known as "revenge porn" sites. The idea is that vengeful people can post humiliating, sexual pictures of former partners, photos often clearly intended for personal use only, if they were taken with consent at all.

Charlotte Laws first encountered these sites in January this year, after her daughter Kayla, who is in her mid-20s, had her computer hacked. In Kayla's email account was one topless photo she had taken of herself – it hadn't been shared with anyone – which was then posted on a notorious revenge porn site, Is Anyone Up. She was distraught, and Charlotte, an author and former private investigator, spent 11 days, non-stop, working to get the picture taken down. One of the nastiest aspects of the site, which has since closed, was that humiliating photographs would be posted alongside details of the person's social media accounts, so they were immediately identifiable.

Laws wanted to find out more about the experiences of those whose images ended up on the site, so began an informal study. She called 40 people – a few men, but mainly women, reflecting the site's make-up – and says that 40% had had accounts hacked, while others were victims of vengeful exes. She spoke to three teachers, one of whom had lost her job due to the site, and another whose job hung in the balance. One woman was terrified the photos would be used against her in a custody battle. Another had seen her business ruined – even though the nude images the site ran alongside her social media profiles weren't actually of her. There was a woman who had taken pictures for her doctor, of her breasts bandaged after surgery, and those had been hacked from her computer and posted. All the pictures were open to biting discussion of looks and desirability.

Laws has been researching possible legal routes for victims of such sites, which has brought her into contact with Mary Anne Franks, associate professor of law at the University of Miami. "What unites creepshots, the Middleton photographs, the revenge porn websites," says Franks, "is that they all feature the same fetishisation of non-consensual sexual activity with women who either you don't have any access to, or have been denied future access to. And it's really this product of rage and entitlement."

Franks finds it interesting that the response to these situations is so often to blame the woman involved. Ali Sargent, a 19-year-old student and activist, says in her school years there were a few incidents of girls being filmed in sexual situations, without their knowledge or consent, and the attitude of other girls was dismissive at best – displaying that dearth of sympathy that distances people from the thought that it could ever happen to them. "It was mostly just, 'well, she was pretty stupid,'" says Sargent.

Franks echoes this. She says the argument goes: "'You shouldn't have given those pictures to that person', or 'You shouldn't have been sunbathing in a private residence', or 'You should never, as a woman, take off your clothes in any context where anybody could possibly ever have a camera'. That's been shocking to me, that people aren't just outraged and furious about this, but they're actually making excuses for this behaviour, and blaming women for ever being sexual any time, at all.

"Even in a completely private setting, within a marriage – it couldn't be any more innocuous than the Middleton situation – and yet people are still saying things like: what was she expecting, she's famous and she's got breasts, and therefore she's got to keep them covered up all the time. I do think it's a rage against women being sexual on their own terms. We're perfectly fine with women being sexual, as long as they are objects and they're passive, and we can turn them on, turn them off, download them, delete them, whatever it is. But as soon as it's women who want to have any kind of exclusionary rights about their intimacy, we hate that. We say, 'No, we're going to make a whore out of you'."