Things ain't what they used to be.

In times of economic slowdown, marketers - even keen to shore up their income - try to persuade businesses that brand loyalty still trumps price-sensitivity in the long run. While difficult times might make people temporarily switch to Value baked beans, failure to promote your branded product means the same consumers cannot be guaranteed to switch back when the good times return.

But what do you do when the product disappears, leaving only the brand - or, in post-modern theory, the signifier replaces the signified? A successful example of this practice was celebrated recently, with the commemoration of the 25th anniversary of the TV police drama Taggart, whose eponymous hero has now been dead for a greater portion of the show's run. Viewers have gotten over the fact of actor Mark McManus's death, and bought into the programme's brand values: a gritty, Scottish, police procedural.

But how far can you take this - and what factors decide the success or failure of such a post-modern brand? Take this year's Paris-Dakar Rally - the self-proclaimed toughest off-road race for predominantly amateur car drivers, usually run between Paris and, err, Dakar, Senegal, local politics permitting. While many people have heard of the race, a greater number might be surprised about the route is has taken when it kicked off its 2009 incarnation last week. Not only did the race not go near either Paris or Dakar, it didn't even take place on either of the same continents as its namesake cities, as it has been run between Buenos Aires, Argentina and Valparaiso, Chile.

This was almost as remarkable, to me, as the news of a reunion concert by The Three Tenors. Despite the obvious handicap of one member of the trio being dead, the marketers would have us believe that, what to most people would be The Two Tenors, is actually The Three Tenors (R), without Pavarotti but augmented by some distinctly lightweight replacements from the world of pop. If such a venture succeeds, it will be proof of the power of brand loyalty over not only good taste and judgement (as if that's something new) but the laws of basic arithmetic.

Where can one draw the line? Could I organise a Beatles reunion without any member of the Fab Four playing, but Ringo's cousin standing in on triangle? Can I sell eccles cakes as "Spangles" if I wrap them in sweetie papers? How much will people pay for the idea of something over the thing itself and be willing to delude themselves for the sake of a sense of belonging engendered by an advertising budget? Given my profession I suppose I should be grateful that, despite the recession, there's still one born every minute.