IT is a glimpse into a world most of us never see.

The notorious website Punternet and a number of similar online resources offer one thing, and they offer it in spades: customer reviews of prostitutes.

Like the numerous popular sites offering reviews of travel destinations, video games, and restaurants, the site is designed to help consumers choose where to spend their money. It is just that in this case the shoppers are (mostly) male punters, and the products are women.

Hidden behind online aliases, such as thephoneman, rocky robin or pickyfellow, men write reviews of sex industry workers they have patronised. Frank, often misogynistic and shocking, their comments are to be brought into the open next week in Invisible Men, an exhibition designed to turn the spotlight on men who use prostitutes and challenge social acceptance of the trade.

After showing for two days at the annual Cosla conference in Edinburgh on Thursday and Friday, the same images will be on show to the public at the Gallery of Modern Art in Glasgow from Saturday March 15 until Sunday March 23.

The content is deemed so shocking it is to be carefully curated and it will be made clear to those visiting the Cosla conference that it is optional to view it.

However, Glasgow City Council's approach in putting the exhibition on at GOMA is less compromising. "We would encourage as many right-thinking adults in society to see it as possible," a spokeswoman said. "It does provide a unique insight into the reality of prostitution and how horrendous it is for the women involved."

This insight is provided not by the women themselves, but through what is claimed to be a random sampling of reviews from Punternet. The words of male customers are superimposed on to blank white face masks and allowed to stand for themselves, with only a price tag added, to show how much the reviewer paid for the encounter.

Much of the content is unrepeatable in these pages. The reviews include violence, crude profanity, and a host of acronyms. So WG is a working girl, PSE is a "porn star experience".

But the excerpts are remarkable for the attitudes expressed by the men to the women involved, and their readiness to complain about poor experiences.

"Just a bad attitude and making no effort to look interested or even pretend to enjoy it... very unusual for a Thai girl", reads one. "Cold as ICE... if you're not interested in the job then go home, don't waste my time and $$", another says.

Some express a kind of concern about the women involved. One is selling sex to raise money because she has a one-year-old baby girl, she tells her reviewer. "I told her to keep the extra and buy the baby a toy and some clothes... this is close to the worst session I have ever had."

A punter worried about the situation of another woman, to whom he paid £40, wrote: "I could have walked out because it crossed my mind she was being trafficked."

He then explains he went ahead anyway. "However the whole experience was a big disappointment and punters should avoid big time."

Linda Thompson, of Glasgow Women's Support Project, is the Scottish Government-funded Challenging Demand Development Officer.

With a remit covering sex tourism, trafficking and other forms of commercial sexual exploitation, she aims to turn the focus on to the purchasers of sex.

She acknowledges many people will be shocked by the exhibition, but says women who experienced the sex trade are not.

"They say 'it was our life'. You read about actual violence which would be rape if a woman were describing it in a police station, and survivors of prostitution will tell you 'that was a daily occurrence'."

However, she doesn't believe the artist behind the exhibition should have censored the content. "People have said the curse words should be blanked out. My attitude is 'you would be offended by the curse words, but not the description of rape?'.

"What is most shocking is not the violence, it is the mundane descriptions of women like pieces of meat. One describes a woman crying and his attitude is 'She should have done her job better. That was a bad experience for me'."

A large part of the intention here is to reach out to the vast constituency of men for whom these attitudes are not the norm, Ms Thompson explains. "These punters never have to answer for their attitudes and actions, they remain out of the public eye. But 10-15% of the population will admit to being involved in the purchase of sex."

Many men will not talk about it for fear of being labelled sad, lonely or sexually inadequate, she says. But others will discuss it with colleagues and friends. And the stereotype is untrue, she claims. "Research shows the vast majority of those who purchase sex have active sex lives with partners. The vast majority of men choose not to do this. The exhibition is saying, 'if you don't agree, if it isn't how you think about women, then speak up.

"Do we want Scotland to be a country where we accept this happening right under our noses? I'd like men to be saying 'please don't be excusing your behaviour by saying it is part of male sexuality'."

Research carried out in Scotland a few years ago with 110 men who bought sex found that many talked about huge levels of regret, Ms Thompson says. Some said they had been pressurised, others hated themselves for their actions. "This is not entirely unproblematic for men. It is not that they don't give a damn about the women." However, claims that such men often look out for the women involved are unfounded, she argues. A dedicated Crimestoppers trafficking helpline launched last January received only three calls all year, she says. "Men are very aware of the terrible circumstances some of these women are in, but choose to do nothing." Worse than that, she says, "they will still have sex for £30, walk out of the door and go on a punter site and complain about it".

Meanwhile, the review sites place a fearful pressure on the women themselves, she says. "They will talk about the constant pressure to get good reviews. The 'commercial' damage of a bad review is potentially devastating, she says. But so is the emotional impact. "Women will talk about the trauma they experience from reading these reviews. One woman told me: "Instead of asking me why I am crying, he runs away to the internet and writes a review, 15 minutes after he's finished. He had no connection with me as a human being at all."