It began on Twitter, of course, as these things do. A user called Craig Nunn (@hrtbps) wrote: "'Why not model for stock images?' they said. 'What could possibly go wrong?' they said." And he enclosed a picture from the agony aunt column in this newspaper, showing a concerned-looking young woman in expensive pyjamas beneath the headline: "I fantasise about group sex with old, obese men".

In truth, the young woman, Samantha Ovens – like all models – did know the risks. Stock shots, in case you weren't aware, are photographs illustrating general themes taken not for a specific purpose but to supply magazines, advertisers or anybody else with a library of useful images. Look up "mean boss" or "couple arguing" online and you'll get the gist. Having modelled for a few, you soon start to notice yourself looking worried about a mortgage here, or suffering from PMT there. But you don't expect this. Not this.

"I opened it up when I was with some friends," says Ovens, who had been tipped off at the weekend by the Twitter whirlwind. "In fact, I was with my partner's mum as well. I screeched with laughter and said: 'Oh. You have to see this.' There's me looking very anxious, and I bloody well would be, wouldn't I?"

The image in question had come from a "Colds and Illnesses" shoot she did two years ago, when she was 36. "I think they had me sneezing, curled up in bed, blowing my nose. There were loads of different versions," she recalls. Being gay in real life, but a specialist in portraying yummy mummies in the press and on television, she is used to a certain level of irony where all her work is concerned. But this was new.

And you do have to be careful. Ovens is a successful model, with past clients including Debenhams, Optical Express, Colgate and British Airways. At one stage she was lucratively installed as "the Harpic Power Plus girl". But big brands take some interest in a model's wider career, and can be reluctant to share them with anything too tawdry. "If I want to keep those kinds of clients, I make sure I protect my image, so to speak," she says. And has the Guardian damaged it? "It doesn't worry me in the slightest." (Indeed, she has gained around 90 Twitter followers as a result.)

There is, in any case, a certain vapidity about the world of stock shots, with all its perfect families and people who look fantastic even when they're ill, so a measure of ridicule goes with the territory. A case in point is the army of female models who are required to pose laughing with salad (a wholesome scene so popular with picture libraries that it has its own fansite). Just yesterday Ovens was looking worried again, this time illustrating "stress" in the Telegraph.

"How can you take it seriously?" she says about the obese old men debacle. "There are bigger things in this life to get concerned about."