The real people behind the spam photos
British UK fashion blogger Poppy Dinsey was horrified to find that holiday snaps of her in swimwear posted on photo platform Flickr had made their way onto porn websites hosted in the US.
"I realised by Googling my name," she said.
"On page six [of the search results] some links had come up to this site. I remember thinking it wasn't the end of the world - they weren't pornographic, they were literally me sulking on sunbeds."
However, the site soon started to make its way towards the front page of the results and Ms Dinsey decided to take action.
"I didn't want people to think I'd put them there," she said.
"Although my pictures weren't pornographic the site was. I tried and failed to contact the site but I was ignored."
Eventually she contacted the site's US host company and it was closed down because of copyright infringement.
"My boyfriend at the time found it very funny, but I was really annoyed about it," she said. "I felt really helpless."
Ms Dinsey takes a daily photo of her outfit for her fashion blog What I Wore Today (WIWT) and admits that there are "an awful lot" of pictures of her around on the net.
"They are taken on my phone - so I own the copyright. It's definitely helped going forward," she adds - although she recently ended up on a fake Facebook profile based in Turkey.
But according to Ms Dinsey's teenage cousins, it's not only anonymous spammers lifting photos for the purpose of faking authenticity on social networks.
"My cousins, who are 15, tell me it's become a thing where teachers and parents steal pictures of attractive teenagers. They then set up [Facebook] accounts to 'friend' their children and their children's friends and see what they're up to.
"They were saying 'Don't friend this girl, it's one of the teachers' - they grow up thinking this sort of thing is more normal but it is unbelievable."
Several newspapers have reported a few individual examples of this phenomenon, but there is no evidence to suggest it is widespread among the teaching profession.
The photo above of a blonde young woman was taken in 2009 for a calendar produced by a Canadian newspaper.
Since then the model has moved house, changed her job, got married and had a baby - but unknown to her that picture is still alive and well on the net, where it crops up from time to time as a profile image on various Twitter accounts.
Her name is Amanda. She was tracked down by journalist Jason Feifer, who was working on a story about "Twitter bots" - fake accounts often set up to tweet links to spam websites or boost the number of followers of genuine users of the social network site.
When Mr Feifer broke the news to Amanda, she told him it felt "creepy" and that she was concerned about what future employers might think - but that ultimately she did not know how to stop the image spreading.
Amanda was not the first spam photo subject Mr Feifer had managed to identify in real life - but she was the only one who agreed to be in his article. At one point he was trying to track down up to 10 images a day.
"Most people don't know what a Twitter bot is - they were suspicious," he told the BBC.
"I didn't want to harass them. It was a shock to them. Their first thought is that it's identity theft - that somebody is parading around as them. It's true in a way - but they're not using their name. In the grand scheme Twitter bots are fairly harmless."
Why does it work?
"Appealing to you on the basis of sex or money is a very obvious trick but the reason spammers do it is that it works," said security expert Graham Cluley, senior technology consultant from Sophos.
"There are people out there who will be tricked time and time again."
Spammers, after all, just want you to click on their links.
These will often either take you to a website selling sexual performance enhancing drugs or a dating site where people posing as women will try to persuade you to send them money. You may also end up with a computer virus for good measure.
There are also no shortage of pictures that are only a right click away - a quick image search for "cute blondes" brings up thousands of photos of women with light hair.
Even Mr Cluley has experienced image "theft" - a picture of him eating an ice cream ended up on an eyebrow-raising website.
"I didn't really care, but if you are worried about this kind of thing, really think hard about whether you want to upload pictures of yourself," he said.
"Maybe it's best to show off your bikini body to your friends when you actually see them."