Rhiannon Harries: Something sinister is going on at the nation's perfume counters

If the commercial breaks in kids' TV programmes are stuffed with ads for the latest toys at this time of year, then those later in the evening seem to be dominated by plugs for perfume. If it's not Sienna Miller pulling irritating cutesy faces for Hugo Boss, it's Charlize Theron strutting about in the buff on behalf of Christian Dior.

There's a sound economic basis for the seasonal war of the fragrance houses, of course – it's said that more bottles of the stuff fly off the shelves on Christmas Eve than during a whole month in the summer.

It seems, to the uninitiated, like the perfect no-brainer present. A little piece of Prada and Chanel at a relatively low price, with none of the pitfalls of sizing presented by lingerie or clothing. But I'd think carefully before breezing into the beauty hall, not least because I used to flog the stuff to earn some cash during my university Christmas holidays.

Brought in by the big names, Christmas casual workers are the mercenaries of the beauty-counter world. With a minimum of knowledge, the aim is to shift as much of your brand as you can, earning yourself the maximum commission. Shop assistants are rarely impartial advisers, but at this time of year they could give Machiavelli a run for his money.

I shudder to think of all the disappointed faces for which I have been responsible on Christmas mornings past. Utterly ruthless, I'd assure bemused fathers that Estée Lauder's Youth Dew (a favourite with the over-sixties) was just the ticket for their teenage daughter. And heaven knows what the grannies made of the gift sets of Carolina Herrera's 212 Sexy I'd foisted on their clueless grandsons.

I like to make myself feel better by thinking of all the Scrooge-like men I persuaded to buy the good stuff, informing them that the perfumed talc really wasn't an acceptable gift for their wife of 20 years. My motives may have been dubious, but at least somebody, somewhere was reaping different benefits.

Really, though, for most women, and indeed men, scent is such a personal choice that grabbing the nearest pretty bottle is a high-risk strategy. It's easily avoided, however, by nothing more complicated than a quick peek in your recipient's bathroom cabinet.

So this week, if you find yourself at the perfume counter and the salesperson starts treating you like Julia Roberts in that snooty Rodeo Drive shop in Pretty Woman because you only want to buy the smallest bottle of eau de toilette, stay strong and stick to your guns! Or else retreat quietly to the accessories hall. Everybody loves scarves.