Ever since Margaret Thatcher rode to power on the back of Saatchi & Saatchi 22 years ago, politicians have overdosed on advertising.
Like hopeless addicts, they perpetually clamour for another fix, anguish at the prospect of rivals outspending them and have impossible expectations of its ability to put the voters on a 'high'. And agencies have been happy to indulge them in the hope that they can replicate Saatchis' success.
The destructive spiral of over-ambition fuelled by ever greater budgets couldn't last and, as the next general election looms, the indications are that the cold turkey period is beginning.
Concord, the outdoor specialist company, set alarm bells ringing last week with research showing that poster campaigns by Labour and the Tories are having far less impact on the public than during the 1997 contest.
One explanation is that it's hard for agencies to be creative when the election result is a foregone conclusion.
But it would be simplistic to blame voter indifference alone for political advertising's failure. The time has come for politicians to fundamentally reappraise the way they communicate.
This will involve some uncomfortable debates. The biggest is whether or not political advertising soaks up large amounts of money for scant reward.
Just like any other agency client, political parties must accept that even multimillion-pound budgets won't sell a product that people don't want to buy.
Labour's election losses between 1979 and 1992 were not because the Tories heavily outspent it but because the public did not regard the party as fit to govern. Nor did a record adspend save the Tories from their worst election result in modern times four years ago. Similarly, the huge amounts of money lavished by the late James Goldsmith on promoting the Referendum Party failed to get a single MP elected - or even save a deposit.
High-profile poster campaigns may help galvanise the party workers to get the vote out. But their effect on most people is being diluted by their ubiquity. Political ads have become an everyday sight.
Mind-sets must change as private polling, market research, focus groups and the internet play a more important role in future elections. Politicians and their agencies will need to show much more ingenuity than at present if they are to get under the voters' radar.