So now every cappucino, latte and espresso in Starbucks is Fairtrade. All Cadbury’s Dairy Milk is too. So are all the bananas in Sainsbury’s. The British government isputting your tax money into the Fairtrade Foundation‘s work with producers in the poorest countries. What’s left to fight about?

The ethics were pretty simple in the early days of Fairtrade. It was a rebel brand; every penny spent was an easy poke in the eye for capitalism and that nasty, greedy Man. But, just as happened with organic, the Man saw that there was money in such fine thoughts, and started to stock Fairtrade. In the late 90s the twirly-whirly green and blue hippy label started appearing on the shelves in the Co-op and Sainsbury, and in 2005 even Nestlé, food campaigners’ great Satan, launched a Fairtrade coffee.

So should we celebrate?

If major global corporations have taken to fair trade, the argument that it’s better to pay producers a living wage is winning. Right? If Cadbury can do it with their most popular product maybe Nestlé and Mars will follow. Note that the price of Dairy Milk is staying the same. Perhaps the big corporations are learning that it’s worth sacrificing a little bit of profit for ethical gain.

Hmm. Capitalism has, as you may have noticed, an unnerving habit of assimilating challenges to it, of turning radical innovations to its own advantage. Hence the string of buy-ups of supposed orthodoxy-challenging, ethical businesses over the years (Innocent, Green and Blacks, Pret a Manger, Ben and Jerry’s, The Body Shop: the list goes on and on).

I can’t think of many examples where that sort of deal has brought any lasting change to the big corp that did the swallowing: generally the original ethical raison d’etre of the acquisition turns out to be just a nifty bit of marketing. And deals with the grateful sellers don’t always survive corporate restructurings or boardroom clear-outs. If Kraft does succeed in its attempts to buy Cadbury, as ongoing talks suggest it could, which of the chocolatier’s non-profit-generating promises will the Americans keep?

So what’s the ethically-challenged consumer to do? Clearly, when these deals happen, you need to take a cold look behind the hype (on this company blog, for example, Cadbury may give you a Fairtrade T-shirt!!) and examine each one very carefully.

Cadbury Schweppes bought Green and Blacks organic, fairly traded chocolate four years ago. Now Cadbury turns one of its many brands – admittedly, Britain’s most popular chocolate bar – Fairtrade. Why not the others? Why not a Fairtrade Crunchie, Wispa and Creme Egg? What, exactly, is the argument against paying people a decent, stable rate for their crops and helping them make their business is sustainable? This is serious stuff – child labour and even slavery is reportedly endemic in West African cocoa farms.

Cadbury says: “This is a step in a long journey for Cadbury and the hope is that it’s just the start.” What does that mean, exactly? Buy the Dairy Milk and maybe we’ll do the right thing by all the children on the cocoa farms?

Going Fairtrade doesn’t mean turning nice all over, of course. Cadbury still puts azodyes in Creme Eggs. According to the union Unite, they have just reneged on a pay deal, despite rising sales this year. They want to move a lot of British jobs offshore. There may be a strike.

Greenwashing is the term used to describe that PR scam where a big corporation boasts about a small ethically-minded change (a petrol company puts solar panels on filling station roofs, say) so it can get away with doing everything else (selling petrol) just as it did it before. Pharmaceutical corporations are adept at it. During the great coffee wars early this decade, the four biggest global coffee companies greenwashed themselves by changing part – often a very small part – of their product line to Fairtrade, or the Rainbow Alliance certification.

Nestlé notoriously pushed its profit margin on coffee up to 26% when prices collapsed at the end of the 1990s, while millions of farmers and their families dropped into poverty. Roundly criticised by Oxfam and others, in 2005 Nestlé launched a Fairtrade certified coffee: Partner’s Blend – “coffee with a conscience”. When I last saw some in a supermarket it was priced at nearly double the shop’s own-label Fairtrade brand – which may explain why Partner’s Blend is hard to find.

It is just one of 640 Nestlé lines and accounts for far less than 1% of Nestlé’s total global coffee purchases. If Partner’s Blend is coffee that “helps farmers, their communities and the environment”, why should we not assume that the other 99% of Nestlé’s coffee does not help them at all?

So – what big corp Fairtrade should you buy? I’d love to know your views. Here’s my rule of thumb:

Don’t buy the new green or fairly traded big brands unless they are plainly a significant part of the company’s business, and you can assume your cash might act as a lever to persuade other manufacturers the same way. And don’t trust go-it-alone “ethically sourced” rubrics – if the label is not Fairtade or Rainforest Alliance, the scheme is usually not as good. Or it’s a spoiler.

So I would support the Co-op, who have led the way in turning all their own-brand coffee, tea, sugar and chocolate Fairtrade – they deserve it. I would not buy Nestlé, in any shape or form. I’m not tempted back over Starbucks’ doorstep yet, because I’m still cross at how long they prevaricated over sourcing all their coffee in a provably ethical manner. (While campaigning during the coffee crisis in 2002, I remember arguing with a Starbucks exec who said with supreme smugness that there was absolutely no need for the chain to go Fairtrade because the company was inherently decent in all its dealings with both customers and suppliers “That goes with our name”. A little later Starbucks tried to trademark the names of Ethiopia’s most ancient coffee varieties.)

But I am going to start buying Green and Black’s again because I think we can accept that Cadbury (who now own the brand) are making more than token changes to their business. Dairy Milk? – I can’t stand it. I’d rather eat Galaxy. But that’s owned by Mars – who own what may be the world’s most widely-stocked brand, M&Ms, and produce no Fairtrade chocolate at all.

There is some trenchant criticism among economists of the Fairtrade model: there are intrinsic problems over how it expands to benefit an entire industry, rather than some farmers at the expense of others. But the Fairtrade Foundation appears to be reacting to this in interesting ways. Fairtrade 2.0 is on its way, and not before time.