It was the US businessman John Wanamaker who is reputed to have first observed that "half the money I spend on advertising is wasted; the trouble is I don't know which half".

But that was back around the turn of the Twentieth Century and it looks like the old adage may have become a bit outdated for this cynical Millennium.

According to a new survey from BT of 600 UK consumers, just three per cent of customers think businesses are honest about their actions regarding what they are doing to become more environmentally or socially responsible.

That means every time your company releases a green ad or constructs a green marketing message just three out of every 100 customers believe you. The rest think that at best you are exaggerating your green record and at worst you are telling outright lies. Forget half your ad budget being wasted, it looks like it is all being flushed straight down the pan.

Advertisers and marketing professionals will, of course, find ways to downplay the implications of BT's poll. They will argue, with no little justification, that green marketing can prove hugely effective if it is done properly and insist that in an increasingly cynical age customers may not believe every claim they hear but that does not stop ads proving highly effective at raising brand awareness and creating a "feel good" factor around a product.

But deep down they must be worried about the sheer scale of the breakdown in trust between company and customer. There has to be a fear that some hardnosed finance director is going to look at the number of customers scoffing at companies' green marketing claims and ask why they are bothering to waste their breath.

Like a philandering husband or a scandal-rocked politician, the green marketing community needs to urgently restore trust if it is to survive. The problem is how it should go about doing this.

The recommendation from most green communication experts can be summed up in two words: stop fibbing.

It is hard to claim customers are being unreasonably cynical about green marketing claims when within days of the BT survey being released the Advertising Standards Authority slammed the Malaysian Palm Oil Council for having the nerve to claim in an advert that its palm oil was "sustainable" and reprimanded BA for an email to customers that claimed the proposed third runway at Heathrow will make it easier for planes to get a landing slot and cut annual emissions by 330,000 tonnes, but which forgot to mention that the extra flights will result in an overall increase in emissions of 2.6m tonnes.

Eradicating such misleading messaging would of course help restore some customer trust, and it goes without saying that it is critically important for all marketing departments to do their upmost to ensure green claims are verifiable, accurate and placed in their proper context. But it strikes that any company attempting to tackle the problem of "greenwash", as it has become known, has to do far more than simply ensure that the lawyers and advertising watchdogs are happy.

Just as the breakdown in trust between politicians and voters has as much to do with MPs mealy-mouthed tendency to evade questions as it does with the still relatively rare occasions when they are caught telling outright lies, consumers' lack of faith in green ads is caused as much by a sense they are being spun as by glaring factual inaccuracies.

Late last year I met with Antony Young who works as director of security and services at IT distributor Bell Micro. As a distributor of IT kit Bell has an interesting insight into the activities of both the manufacturers pushing new green technologies and the retailers and resellers who actually have to sell the stuff.

Young's view was that despite all the hype from the global IT giants about greener, more energy efficient systems demand for the technology had largely disappointed thus far. He attributed this to "snow-blindness" amongst customers who had become jaded by the sheer number of green marketing messages emanating from IT companies.

It's an analysis that will sound worryingly familiar to countless other sectors. It's not that you could accuse any of the IT companies' individual green marketing campaigns of being inaccurate or untrustworthy or misleading, it's just that there were so many of them that customers assumed vendors were just jumping on the bandwagon. Sadly, good green adverts and campaigns that could never be described as greenwash were still regarded as such by cynical customers.

The only answer to this problem is for marketing professionals to display a characteristic that hardly comes naturally to them: restraint.

As the green marketing sector matures, businesses will have to learn that inundating customers with messaging every time they launch a new product or service that is fractionally greener than the previous version will only prove counter productive in the long run.

As Young observes, companies would be advised to "keep their powder dry" for the green products and services that really outperform the rest of the market, rather than waste precious marketing capital on yet another offset scheme or fractionally more energy efficient system that offers nothing new to jaded customers.

It is extremely difficult to display such restraint, particularly when businesses are increasingly excited about their environmental initiatives and keen to show them off to a growing band of environmentally conscious customers. But resisting the temptation to trumpet every green initiative from the rooftop may ultimately help restore trust in environmental claims and ensure that customers greet the really big and meaningful green announcements with more than just a weary shrug of the shoulders.