IT is just a colour.

That's what I wanted to say when I heard the fuss over the pink-hued van used by Harriet Harman to launch her Labour Woman To Woman female vote recruitment campaign. Some called it the Barbie Bus. Others made comparisons with the Sheila's Wheels advert. Harman, seemingly jokingly, described the colour as magenta. Her Labour colleague Gloria de Piero called it cerise. Many seemed to consider the choice of hue to be "patronising" or "condescending".

But pink isn't just a colour. It's a nasty smell, too, if you go by the slogan of Pink Stinks - a campaign which battles against the use of pink to market gender-stereotyped products to girls. Pink comes with baggage. Once deemed an appropriate colour for boy babies because of its strength, it took off as a marketing tool to sell products and from the 1980s onwards become increasingly pervasive and associated with segregated children's play.

Through the breast cancer pink ribbon campaign, it has also come to stand for a kind of non-politicised female solidarity. Pink, in other words, currently speaks of femininity - and has adeptly been used in marketing to sell a great many messages and products. So it's not surprising that some saw a pink stink in Labour's Woman To Woman bus.

Here we are again, talking about the problem of the women's vote and how to win it. As happened during last year's referendum campaign, we are wondering why so many women are undecided.

On one level Harman's bus seems to have worked: we are still talking about it. The only problem is that mostly people aren't talking about politics. They aren't talking about the fact that Labour's record on putting forward women candidates far exceeds any other of the major parties in Westminster. They aren't talking about the upcoming Labour women's manifesto to be published in April. Mostly what they're interested in is the bus, and trivial details like whether the female driver stalled it on the way to the shopping centre.

The Woman To Woman campaign is, says Harriet Harman, a response to disaffection among women. Election turnout among women fell 14% between 1992 and 2010 - compared with 11% among men. No-one seems to know why. Women, it's assumed, were feeling more alienated.

This fall-off in voting is surprising. In the USA, women are currently more likely to vote than men. Here in Scotland the polls following last year's independence referendum, suggested a rough parity in terms of gender turnout, even if there was a gap in how the genders actually voted. I didn't see much disaffection among Scottish women during the referendum campaign; nor did I see it among the young. And this fact alone reminds me of something that Women For Independence founder Carolyn Leckie told me in an interview last summer. Women, she said, were less likely to feel entitled to have a say in the way their world was run.

Those feelings of entitlement can change. They changed a little here last year. They are altered by seeing people like oneself in power, by feeling more connected to groups that might influence government decisions, or just sensing that one's vote might count. In 2012, for the first time in US history, America's blacks voted at higher rates than whites, lifting Democrat Barack Obama to victory amid voter apathy.

So a very conspicuous campaign like Woman To Woman might help create a sense of entitlement. Pink may even play a part in that. The colour has, after all, been used to market Lego, Nerf guns and bows and arrows to girls. It's been used, in other words, to make girls feel they are entitled to these things, that they belong to them.

I write this as a parent of two sons, who all too frequently finds herself trying to tell them that pink, and some of the girl culture that comes with it, is OK and valuable and good. I try to tell them that they can do some of those pink things too; or that they shouldn't laugh at them. But then something like this happens in the adult world of power and it seems yet again that the overwhelming message is that pink stinks.

I've long been uncomfortable with those who dismiss pink culture as trivial and shallow. Too often what they're dismissing is not the cynical marketing of the colour, but the characteristics of femininity associated with it: warmth, caring, an interest in friendship. Some of that knee-jerk reaction is there in the dismissal of Harman's van as a "Barbie bus".

It's there in the Daily Mail article that says the slogan, "Woman to Woman", has "the ring of a sanitary towel logo". It's there in the Twitter quips suggesting it might be more appropriate for a hen night.

Is it the bus itself that is sexist and patronising? Or is there something misogynistic in the disdain for its colour? Could it be that people, women as well as men, can't bear to see anything as boldly feminine as pink, in the traditionally masculine world of politics?