Dressed in jeans and a hoodie Roseanne glances around Glasgow's red-light district, wanting to be seen by some but needing to remain unnoticed by the police.

It's only when she's off the streets in a quiet pub that she relaxes. Her freckled face may be scarred by drug use and abuse, but it lights up when she smiles, making her look younger than her 40-odd years. She laughs while telling stories about two decades in the sex trade including how she once dressed up in bondage gear for "her girls" as a joke only to answer the door to a policeman.

She has worked across the spectrum of Scotland's sex industry: in a private flat; as a madam; in an Edinburgh sauna and for herself on the streets of Glasgow – racking up 53 convictions, from running a brothel to persistent soliciting.

Her jokes about her work – she blames a former boyfriend for getting her into it, to get money for drugs – are interspersed with tales of violence, told in a matter-of-fact tone: how some of her teeth are missing because she was attacked with a dog chain, how her four children were taken away from her, how her face was reconstructed after a run-in with a punter. "I feel like I'm about 500, all the things I've seen," she says. "Sometimes I just don't want to get up."

Just how to help women such as Roseanne – and deal with the industry she works in – is the subject of fierce debate in Scotland. A bill that would have made the purchase of sex illegal failed last month to get through parliament, but sex workers are worried that an apparently tougher approach towards policing in the capital could herald the start of a new era.

In April Scotland's eight constabularies merged to become a single police force. The police's approach has, in the past, been very different in Glasgow and Edinburgh. Brothels in the capital were ignored while others were being shut down an hour away in Glasgow. But the era of tolerance in Edinburgh appears to be over, as indicated by raids on saunas in the city last month.

The raids, involving 150 police officers entering seven saunas and 11 other premises around the capital, have created a climate of fear and distrust, according to the sex worker advocacy group Scot-Pep. The organisation has warned sex workers to take extra precautions and issued a statement wondering "whether this is a taste of things to come".

Police said they had evidence of human trafficking and links to organised crime as well as "discrepancies in licensing regulations", but have given no details on the number of victims, where they were from or where they worked.

It is an unexpected turn of events in Edinburgh, which had followed what proponents argued was a pragmatic "don't look, don't tell" policy to sex work, licensing a dozen or so saunas for "entertainment purposes". Some see the influence of policymakers in Glasgow. There, a zero-tolerance approach to sex work has resulted in ready punishments for soliciting and kerb crawling, and city leaders vigorously supported the criminalisation of the purchase of sex bill, which sought to implement the "Nordic model" in Scotland.

The international debate around the Nordic model, the criminalising of buying sex which has been enforced in Sweden and other countries, meanwhile, intensified this week following the fatal stabbing of a 27-year-old sex worker and activist in Sweden known as Petite Jasmine.

A prostitute waits for business in central Stockholm in Sweden, where the Nordic model has stabilised numbers of sex workers. Photograph: Reuters

Her former partner has been arrested on suspicion of murder. George Lewis, of Scot-wsp, said: "The death of Jasmine is a real indictment of the Swedish policy – it feels like a dam has burst."

A second sex worker, a 24-year-old transsexual known as Dora was also stabbed to death this week in Turkey. This Friday, 15 protests will take place outside Swedish and Turkish embassies in 10 different cities, including Glasgow and London, to call for rights and safety for sex workers.

The 'Nordic model' bill in Scotland, championed by the Labour MSP Rhoda Grant, failed to get the required amount of support across three parties in parliament, after SNP parliamentarians refused to back it. But the debate around making buying sex illegal has raised awareness of abuse, according to Grant. "Even getting the bill this far has meant that people who didn't think prostitution was a harmful problem in this country have had to think again," she said. "Obviously I am disappointed but this is not over. People are still suffering, they are still being abused by those who would make profit from them and that means you cannot just give up, you have to keep on going." Grant said she would continue to raise awareness and look for opportunities to keep the debate live. "Changing the way society views prostitution is as important as changing the law - we have to say no, it is not acceptable to buy and sell another human being. That should not be acceptable in our society."

The politician's arguments around reducing the demand for sex have been pilloried by campaigners. "This is not a protection issue, it's abolition and it's a moral issue. There are some people who just find the exchange of sex for money morally repugnant," says Laura Lee, a Glasgow-based escort allied with ScotPep. She argues that were buying sex to become illegal, sex workers would have less time to vet possible clients, and would be pushed to work in less visible areas.

She adds that the UN-backed Global Commission on HIV and the Law has called for sex work to be decriminalised, stating that the Swedish model had worsened conditions for prostitutes.

Lee, who started work in a Belfast parlour, believes there are inaccurate perceptions of sex work: "People think it's either Belle de Jour or drug-addicted sex workers, but the vast majority are in the middle. There will be days they enjoy their job and days that they don't."

Speaking after a day of working in an Edinburgh sauna Anna, 28, who moved to the city from eastern Europe two years ago, does not tell her friends what she does for a living but insists she finds the work fun and rewarding: "Men are quite simple, and when you please them they are generally grateful," she says.

Her focus, however, is on the fact that it is well-paid and flexible. "What am I going to do instead? Flip burgers? Make £200 to £250 a week? Here I make that in a day," she says.

"People think of my clients wanting something from me, but what I want most is something from them." A former police officer is less complimentary: "The clientele in these places are by definition pretty sordid, highly manipulative and sleazy," he says. "But you have to keep the lines of communication open, even with people like that." But Anna does not want sex work legalised, which critics argue has led to spikes in the numbers of sex workers in places such as Germany where prostitution is legal, resulting in low prices and "flat-rate" brothels where sex workers are expected to have sex as many times as a client demands. "That might help the clients, but I don't see how it helps us," she says.

Other groups working with former prostitutes argue that brothels are hubs of organised crime and that many sex workers are injured physically and mentally by the work.

"People don't seem to recognise that inherent in prostitution is the fact that you constantly have to have sex with people you don't want to have sex with [...] if it's unwanted, it's damaging," says Linda Thompson of the Women's Support Project (WSP) in Glasgow.

"There is this rhetoric of the woman who is empowered by sex work, but we recently heard from a young woman who has said this almost destroyed her. The way she put it was: "Who wants to hear from an unhappy hooker, who was the happy one? The pro sex-work lobby frame prostitution as a positive choice and if it didn't work out for you, you made the wrong choice."

The WSP had supported Grant's bill as a step in the right direction of tackling demand. Thompson's co-worker, Jan McLeod, says: "This is about a much bigger picture. Who remains invisible behind this supposed fight between feminists and pro sex-work activists? The punters. For us, it's about changing attitudes to men who buy sex. Punters have to step up and take responsibility for what they are doing."

Roseanne puts it another way: "A lot of these girls kid themselves – no one does this for the view."

Edinburgh had an unofficial tolerance zone until 2001 while in Glasgow the Glasgow Community and Safety Services [GCSS] runs a targeted exit scheme. "We don't wait until [prostitutes] say they want to exit and we share all our info with police," says senior operations manager Louise Belton. "We try everything to engage with them. That could be a charge, which puts them in a system where they have support."

Following global trends, sex work has moved off the streets in both cities, as women organise meetings online or by phone. In the past three years GCSS has worked with about 450 female street workers, while police figures last year estimated that there were 898 indoor prostitutes in Glasgow. In Edinburgh, estimates from Scot-Pep suggest the industry – like the city – is smaller, with about 700 indoor workers – 200 in saunas, 350 independent escorts and 150 agency escorts as well as 80-100 women on the streets over a year.

The different approaches the cities have taken is reflected in the number of arrests: 33 women were arrested for soliciting in Edinburgh in 2010-11, and 21 the following year. In Glasgow there were 47 soliciting offences in 2010-11 and 86 last year.

Purchasers of sex are not tolerated in the city either: the number of people caught kerb crawling in Glasgow was up 80% in 2011-12 – the highest figure since legislation was introduced.

Escort Laura Lee in a flat used for sexual services. Photograph: Murdo Macleod for the Guardian

How the law works in other countries is under closer scrutiny than ever as France and Northern Ireland consider criminalising the purchase of sex, Israel moves to strengthen laws around soliciting, and a campaign to legalise sex work gathers pace in China. Yet dispassionate analysis of the abolitionist versus legalisation arguments is problematic, with reports written from both perspectives often heavy on opinion and light on data. Differences between street workers and those in brothels and flats are stark, yet some reports conflate the two. The Nordic model – operated in Sweden, Norway and Iceland, which all top gender equality tables – has been credited with reducing organised crime and stabilising numbers of sex workers in Sweden, but numbers have increased in neighbouring countries. Meanwhile a report from New Zealand – where selling sex was decriminalised in 2003 – found the law had "little impact" on numbers, although some residents complain about a proliferation of explicit advertisements for brothels on local radio, and are opposing a 15-storey "super brothel" in Auckland. While the same report found "some better working conditions" in New Zealand after the change in the law, workers still felt legislation "could do little about the violence that occurred".

A 2001 report found 81% of street sex workers and 48% of indoor workers had experienced violence, while in December a London School of Economics report concluded that where prostitution was legalised reports of human trafficking increased. Paul, a gay sex worker and masseur working from a flat in Glasgow insists that transparency is the only way to improve the health, safety and status of sex workers. Speaking in a grubby cafe in the east end in Glasgow, he says: "When people talk about abolition, they are talking about our lives and our jobs. But are they going to find us jobs that are as well paid or increase the benefits that are always being cut? If you don't tackle people's economic and housing needs, then how can you expect them not to take measures to look after themselves?"

Back in Glasgow's red-light district, Roseanne pulls a letter out of her bag before going back to work. It's from Routes Out, a GCSS programme that aims to get women out of prostitution, which has promised to find her space on a long-term drug rehabilitation programme. She wants to stop working on the streets. She has a new boyfriend – a good one this time.

"It would kill him if he found out," she says. But more than anything else, she is tired of looking after herself. "It's hard, I've got bills to pay and benefits are getting tighter," she says. "But I just don't want to do it any more, it's just not worth it."

Some names have been changed