Walk along Argyle Street in Glasgow, and you find yourself wading through a sea of Primark bags. I have never bought anything from Primark. That said, a pair of their women's black pants has recently surfaced in my washing. Would the owner please claim them before I use them as a duster.

I have several problems with Primark. I come from a make-do-and-mend generation, where clothes were expected to last for months and years. Should I ever decide to sue my parents for neglect, I would cite as grounds that I never wore a new pair of pyjamas until the age of nine because I was cruelly condemned to wear out those of my cousins, previously cast off by my sister. So the whole idea of a weekly shopping trip where you load up a capacious receptacle the size of a lobster creel with disposable clothes - just as you might load up your trolley with food - is totally alien.

Then there is the "retail therapy" thing. I have never found clothes shopping at all therapeutic, least of all when it resembles a rugby scrum. Last week, by way of an anthropological exp-erience, I went into Primark's new, supposedly more civilised, flagship store in London. People propped themselves up on the wall outside because they couldn't carry their fistfuls of bags any longer. Flushed, hyped-up shoppers were frenziedly binge-buying clothes that they weren't entirely convinced that they liked, and might never even get round to wearing. It was like watching a convention of fatties mounding up their plates at an Eat-As-Much-As-You-Can-For £1 banquet.

It doesn't take much in the way of numeracy skills to calculate that "cheap chic" comes at a price, one that is likely to be borne, not by the shopper, but by the person who made it. If you pay £5 for a pair of jeans, and deduct shipping, packing and distribution costs incurred getting them into stores, then it stands to reason that the Bangladeshi/Mauritian/Cambodian seamstress who ran them up isn't likely to receive too much in the way of remuneration. In Bangladesh, garment workers typically earn 5p an hour and work a 70-hour week, according to a War On Want report that interviewed 60 workers from six different garment factories. The report also found that, while Primark, Tesco and Asda had all signed up to a set of principles to provide decent working conditions for factory staff, some of their suppliers were "regularly violating" such rules.

Primark, Tesco, Asda, and Top Shop have all been accused, by charities such as War On Want and Oxfam and by international trade unions, of tolerating low pay and poor working conditions in factories operated or sub-contracted by their suppliers. Such allegations are vigorously denied by all these companies. Primark and Tesco point to their membership of the Ethical Trading Initiative as evidence of their good practice. They insist that their low prices are down to skilful manipulation of logistics, rapid turnover and economies of scale. I know who I am more inclined to believe.

Prices of women's clothing in Britain have fallen by one third over the last 10 years and any fashion magazine is testament to how cheap chic has become respectable. Conspicuously wealthy footballers' wives brag about their latest style bargains, a rip-off of Roland Mouret, perhaps, or a "Primani" suit. The heads of fashion houses whose clothes are still made in Europe by well paid, full-time staff benefiting from employment law, must be sick as a parrots to see their designs copied (invariably badly), run-up in some foreign sweatshop, and on sale on the high street only days later.

Stripped of any ethical dimension, the economic logic of ever cheaper fashion is remorseless. Think of Burberry, that once quintessentially British brand, that this year closed its South Wales polo shirt factory, with the loss of 300 jobs, and transferred its production to China to cut its costs, despite making £110 million profits. As economists keep pointing out, poor people in far distant parts of the globe have a perverse economic advantage over counterparts in countries with more equitable laws and higher living standards. Their labour comes cheap, and there aren't any unions around to defend them from enforced overtime or instant dismissal.

The recession in UK manufacturing caused by cheap imports makes it increasingly difficult to find clothing that is made in Britain. More competitive garment industries in Europe, such as Turkey, Greece and Portugal, are under constant price pressure from fickle buyers who can move their business further east and south at will. By starting a ruthless price war, volume high-street chains have apparently panicked mid-market companies into following suit, where £5 will buy you three school blouses and you can find two cotton polo shirts for £2 - doubtless a boon for hard-up parents.

But is it acceptable to make people here better off by taking advantage of desperate people elsewhere? That injustice is summed up by one Bangla-deshi worker who told ActionAid: "I sit all day making school uniforms for foreign children. I feel so sad that I can't afford to send my own children to school."

The poorest of the poor in Britain are positively feather-bedded compared to garment workers of China, Vietnam or Sri Lanka. And make no bones about it, there are plenty of affluent people loading up with £5 jeans, just because they are greedy and like a bargain. It's time they faced up to who is footing the bill.