Lesson: if you stay in the world's newest, super-luxury hotel - even in the spirit of journalistic inquiry - clean out the contents of your wash-bag. My wife and I (feeling like Neil and Christine Hamilton, without the affrontery or the hair lacquer) joined 70 other guests for the first night of a reborn Parisian legend: the hotel George V.
I had expected a culture clash - but humiliation by wash-bag had not occurred to me.
That apart, the culture shocks were mild and pleasant. After two years of closure, the George V, the hotel which once epitomised the ephemeral glamour of the 20th century, re-opened on Saturday as a new kind of luxury hotel for the 21st. This means the Internet in every room; it means a TV, video and video-game ensemble which makes your bed feel like the cockpit of an Airbus; it means a swimming pool and a health spa, and a little leaflet in each room, suggesting jogging routes through Paris.
It also means a generational shift from the attentive but stately and judgemental atmosphere of the Ritz or the old George V. The new staff (attentive, but startlingly young) seem to have been trained to avoid gazing at you as if they have the power to X-ray your bank account (an impression you still get if you happen to wander into the Crillon or Bristol, or the other Parisian hotels for the super-wealthy).
It is as if the reborn George V - beyond the high-tech gadgetry - has been updated spiritually for a new, more informal world, in which millionaires are just as likely to turn up in baseball shoes as in pearls.
For the last two years, the George V, on the avenue of the same name off the Champs-Elysees, has been the most expensive building site in the French capital. Its owner, Prince Alwaleed Bin Talal Bin Abdulaziz Al Saud, nephew of Saudi's King Fahd, paid pounds 90m to the British hotel group, Granada, for the hotel in 1996.
He has since spent another pounds 70m on ripping out the interior and starting all over again. The work took twice as long as initially envisaged because the builders were obliged to observe gentlemen's office hours - from 10am to 5.30pm - so as not to disturb the wealthy and powerful neighbours on this, one of the most exclusive avenues in Paris.
There was much sorrow when the old George V closed. I went to the vast auction-cum-jumble sale in October 1997, at which much of the hotel's furniture and memorabilia were sold off. It seemed at the time that the George V was selling its memory bank and its soul. Anything associated with a celebrity name sold for two or three times its anticipated price.
A pair of snot-coloured Staffordshire porcelain dogs which had once stood in Greta Garbo's room went for pounds 4,500. A double bed in which the Rolling Stones had slept (all of them?) for pounds 4,300. A potty used by General Dwight D Eisenhower - when the hotel was briefly his staff headquarters in 1944 - for pounds 2,800.
Ten ageing multi-millionaires, who had been living in the hotel for as long as anyone could remember, had to be evicted into the Prince of Wales hotel next door.
The George V is not an old hotel by Paris standards. It was built in 1928, in Art Deco style, by American hotel tycoon Joel Hillmann. At the time, it was the only hotel in Europe with an en suite bathroom for every room. For the next four decades, it was one of the places to be seen if you were part of a certain kind of jet set: the rich and energetic, rather than the rich and idle.
It was especially popular with Hollywood stars and Middle East potentates (both of which groups have long since emigrated to the Bristol hotel on the other side of the Champs-Elysees).
The cast list of former guests also includes Gene Kelly, Gary Cooper, Vivien Leigh, Burt Lancaster, Sophia Loren, John Wayne... In the Sixties, Marlene Dietrich booked a suite at the George V for years at a time. In its heyday in the Thirties, the hotel had its own air-taxi service, and chauffeur-driven cars direct from the French Atlantic liner ports of Cherbourg and Le Havre.
In 1964, on their first visit to Paris, the Beatles stayed in the George V. A grand piano was moved into their suite. According to one account, it was here that Paul McCartney and John Lennon wrote "Can't Buy me Love". The refrain - "Money can't buy me love" - was appropriate for what was still one of the great gathering places for the immensely wealthy.
Not for much longer, however. The George V was once compared to an ocean liner, moored just off the Champs-Elysees. Like many an ocean liner, it proved unable to move with the times. It was starved of investment and its glory days faded with its furnishings.
In the Eighties, after its purchase by the British Forte group (later taken over by Granada), the George V slipped out of the premier division of Parisian hotels. By the early Nineties you could go there on package tours for pounds 100 a night. Even walking off the street, you could stay there for less than pounds 200 a night (against pounds 300 for the cheapest room at the Crillon or the Ritz).
Prince Alwaleed Bin Talal Bin Abdulaziz Al Saud had spent part of his childhood in the hotel. He made it his mission to restore the George V to its former pre-eminence - but also to make it the most technologically advanced luxury hotel in the world. Rather than close the hotel floor by floor, or wing by wing, he ordered the whole place to be closed and virtually gutted.
Some of the best furnishings were kept, including a dozen celebrated 17th and 18th century tapestries from Aubusson and Flanders, which are the centrepieces of the new hotel. The rebuilding has recreated the original Art Deco style and seems to take its colour scheme from the tapestries: all pale slate-blues and ochres and creams. The effect is stunningly beautiful.
The new George V (managed by the Four Seasons group, of which Prince Alwaleed is a major shareholder) also plans to reclaim its long-lost place among the best restaurants in Paris. The main restaurant, Le Cinq, has recruited one of the best younger French chefs, Philippe Legendre, 41, who has been awarded three stars in the Michelin guide at the Taillevent restaurant in Paris for each of the last 10 years.
Since, unlike Neil and Christine, we were paying for ourselves, we did not sample the more expensive items on the menu or wine list. It was only afterwards that the maitre d' told us that it was half-price for the first night because the kitchen was not yet up to full speed. Everything seemed fine to me: my crab cannelloni and roast wild duck were extraordinary.
The dress code in the new George V has yet to establish itself, but the first-nighters were mostly ostentatious-casual: smart jackets, discreet jewellery and crisply pressed jeans. There was one celebrated TV newsreader. But there was also a middle-aged mum with an 11-year-old boy, who spent most of the dinner reading a comic-book.
Earlier, the same pair just beat me to the honour of being the first to use the new George V's underground swimming pool. I had to be content with being the third person to dirty the pristine tiles of the changing rooms. I laboriously swam up and down, while the lifeguard anxiously paced alongside me. Was it his first-night nerves, or is my swimming really that bad?
No-one would pretend that the new George V is cheap. It is back in the minimum-pounds 300-a-night class. To have your knickers washed in the laundry costs pounds 4.50, which is more than the price of a new pair, even in Paris. This is perhaps a subtle way of saying that only people with very expensive knickers are expected to stay there.
On the other hand, judging by the welcome we received, no one need feel out of place. Anyone who wished to save up and blow a little money on a luxury weekend here in Paris would get far better value than the foreign tourists who are charged up to pounds 200 a night for mediocre hotels in central London.
Jean Cocteau said that a great hotel should be "a reflecting mirror" of the vanities and achievements of its age. The new George V, both exclusive and relaxed, fits the description. In the end, however, the character of a great hotel also depends on the richness of its history, something the new George V has partly washed away.
Money can't buy a new soul and a new memory bank. Only the guests and the passing years can supply those.