He hesitated for an uncomfortably long time. Then he laughed. "Of course," he said, "animal testing and tobacco. Especially animal testing, you just can't find a quant agency willing to do the research these days."
I, on the other hand, was in earnest. We've spent weeks looking at pictures of obese children in the newspapers. For years, stepping over piles of vomit (happy hour cocktails, sponsored by your friendly global drinks conglomerate) has been the town centre norm.
As the recent Health Select Committee report on childhood obesity and the admission that police have lost control of town centres to binge drinkers attest, this is a crucial debate for agencies.
It's easy to resort to the excuse that we now live in a sedentary culture with more full-time working parents buying more convenience foods. This argument has been put forward in these pages and by the industry for years now. And yet, and yet ... shouldn't agencies have an ethical perspective, a higher consciousness that's about getting their own houses in order?
You can easily see why they would not develop such a point of view. Business is business, if a product is legal to sell it should be legal to advertise and, if there are some small qualms about expediency and social trends, these can always be soothed in one way or another.
This may sound unkind, but what other answer is there? For most big shots in advertising, their career progression inevitably distances them from the coalface. Although advertising may be the product they are selling, they themselves cease to be advertising executives and become instead international business people with budgets to meet.
It is only when agencies are credited as wielders of such vast influence over our food and drink consumption that they are forced to take responsibility for the consequences of their actions.
And that is what is so depressing about agencies' current stance towards the level of criticism received. Far from grasping an opportunity to act as one, the industry has moved to a state of denial.
Agencies are taking their cue from media owners who (while plastering the debate all over their news bulletins and front pages) are not giving an inch on the food advertising issue. If you take away one of the funding streams for children's television, the broadcasters say, childrens' programming will be reduced as a result.
And yet clients appear to want a more profound debate. In this respect, agencies may be listening at their peril to the media owners over their clients. All around us there are images of gorgeous young things in glamorous settings, enjoying a drop of the hard stuff, playing neatly into the hands of all those who question the efficacy of self-regulation. All around, too, there are clients busy tunnelling their way out of conventional media and into less regulated areas.
The dilemma for agencies is whether to exploit current advertising freedoms while they can, fighting every inch of the way; or to come to terms with their acknowledged role in shaping demand and have a genuine debate about the relationship between clients, brands and consumers. It may lead to the same ultimate outcome, but it would certainly play to the bigger picture.