Occasionally, the faded painting in the loft turns out to be a Rembrandt, or the old pot that's been used as an umbrella stand is actually a lost masterpiece by the sculptor Rodin. This is what happened to a British couple whose parents' Chinese vase brought a record amount at auction last week.
With heirlooms, trash does sometimes become treasure
One of the most popular TV shows on UK television at this time of year is The Antiques Roadshow. The premise of the programme is exquisitely simple: take a series of fine art specialists to a large country house, alert the local populace, and then merely sit back with a fleet of cameras and wait for them to turn up with their family heirlooms.
The show ticks all the boxes for perfect Sunday evening family viewing: stately homes, old collectibles and lots of eccentric experts in bow ties and bristling moustaches (and that's just the women). Oh yes, and there's one further crucial attraction, never acknowledged but surely the most alluring of all: the possibility of witnessing the sudden acquisition of spectacular wealth.
Each separate valuation follows the same climactic process - the supplicant hands over their object, perhaps an old teapot inherited from a grandparent or a painting that's been languishing in the attic - the expert scrutinises it, turning it over in their manicured fingers, perhaps deciphering the faded hallmark on the base or explaining the item's original purpose. But then we come to the money shot - the moment when the expert estimates how much the item is worth.
As the camera hones in on the face of the poor old punter you can always see dollar signs reflected in their eyes. What if? What if this old bit of junk is really a Picasso or an ancient Etruscan artefact? What if I'm fabulously wealthy and never knew it?
For the majority, of course, the result is disappointment - or worse. "Well, Mavis, this would have been worth quite something, but because of this crack in the lid which was caused when you knocked it getting out of your car on the way here this morning, I'm afraid its only worth a fraction of the original amount."
But occasionally the faded painting in the loft turns out to be a Rembrandt, or the old pot that's been use as an umbrella stand is actually a lost masterpiece by the sculptor Rodin.
When it happens, Brits being Brits, they never show their true emotions: particularly when connected with anything as distasteful as commerce. That would never do. So instead, they gulp heavily and respond with something suitably disinterested, as if the prospect of becoming a millionaire was the last thing on their mind when they arrived.
"Oh golly, that's a bit of a surprise," they reply weakly when told they've just become richer than their wildest dreams. The joy for the viewer is in seeing the customer trying to disguise their glee under a mask of polite respectability. No wonder the show has become essential viewing.
It has also caused an entire generation to ferret about in their lofts and garages in the hope of discovering a life-changing knick-knack: and in truth there have been some truly spectacular discoveries of late. A painting by the celebrated artist Joseph Farquharson recently fetched $110,000 (Dh404,000) afterhaving hung in a woman's sitting room for nearly 40 years, while an old car discovered in a lock-up garage turned out to be a 1937 Bugatti Type 57S Atalante, one of only 17 ever produced, and worth a cool $8 million.
But such amounts are little more than loose change when compared to the sum achieved last week. An 18th century Chinese antique vase, found by a brother and sister during a routine cleaning of their parents' house in north-west London, was sold at Bainbridge's auction house for $82 million after it was discovered that it hailed from the ancient Qianlong dynasty of China.
As the bidding soared into the stratosphere, the dazed couple had to be helped from the auction room in a state of shock, and were only able to return having been revived with smelling salts. By this time they were wealthy enough to afford not only the salts but also the entire mountain range from which they'd been mined.
Inspired by this tale, I've spent the last few days rootling around in my own attic in search of buried treasure. While my old roller blades and a stained futon from my student days may not fetch much, I have high hopes of finding something - anything - that will enable me to live in the manner to which I'd like to become accustomed.
Still, best not get carried away. Urban legend tells of another hopeful individual who discovered a large ancient iron receptacle at the back of his loft. After nearly a week wrestling it from its moorings and down three flights of stairs, he eventually drove it up to London to have it appraised.
"Well Mr Smith" said the expert after a cursory examination, "it appears you've bought me your domestic hot water tank."
Michael Simkins is a writer and actor based in London