It is 9:30am in Karlovy Vary in the Czech Republic, and I have settled in for a good morning of watching elderly Slavs scald themselves. They approach the thermal springs for which the town has been famous since medieval times. The hottest one exits the ground at something approaching 80 degrees. The pensioners who flock to Karlovy Vary to ‘take the waters’ arrive each morning and fill up funny little porcelain drinking pots – half-beer stein, half-teapot – with water. These, the invention of a 19th-century quack called Jan Becher, are supposed to maximise the medicinal properties of the waters as well as cooling them to a drinkable temperature. Elderly ladies hobble along with these pots, before taking a tentative sip and then writhing around making noises like dying gremlins. They have discovered that the liquid has remained, despite Jan Becher’s magic, at a painful 70 degrees. It happens every day, without fail.

There are other springs that flow at more reasonable temperatures, but all have their own threats. One stream advertises its laxative properties when drunk at a particular temperature. It only says so, however, in Czech, leaving many visiting Russians and Germans hopping towards the town’s scantily available lavatory facilities. Another spring, in the ornate Park Colonnade, is said to be a cure for hepatitis, yet it is confusingly close to a different spring that is exceptionally high in carbon dioxide content. It tastes absolutely, irredeemably foul. I deliberately slow my walk to watch as one young man explains to his friend the health-giving properties of the water, before spitting it out with gusto, like he’s just eaten the contents of a three-day-old ashtray.

My people-watching lasts a good while before I saunter back to my room at the Grandhotel Pupp, stopping for one of their alcoholic coffees which contains, mysteriously, chunks of coconut. Later, I will sit in a very hot room with a German pensioner, a nervous couple of Czech newlyweds and a man whose terrifying silence telegraphs his Russianness more clearly than if he had opened his mouth. All of us will be completely naked. This is the spa world of Mitteleuropa. Wes Anderson meets Yuri Andropov.

It is the faintly unsettling atmosphere of decline that brings me back to Karlovy Vary every year. I love the Grandhotel Pupp, with its lift muzak of 00s pop hits played on a tinkling piano. I love the Hotel Imperial with its private funicular railway and mile-long corridors. The staff – almost all locals who are bemused as to why anyone would go there in the first place – tease me for my affection and my accent. ‘You speak like this,’ one of them says to me, before miming a flaccid arm, ‘like you have mrtvice’, which, flatteringly, is Czech for ‘a stroke’.

For all the idiosyncrasy of Karlovy Vary’s appeal, however, I am not alone on my visits. The region of which this crumbling fantasy town is the capital receives 1.3 million visitors a year. People come for various reasons and have done so for many years. Vast hotels, parks, promenades, spas, casinos, golf courses and a racing hippodrome are testament to what the resort was in its pre-World War One heyday. Now, depressed-looking tourists rattle around them, old pennies in an ornate biscuit tin.

What do they do once they’re in Karlovy Vary? They can’t all, like me, be there for the people watching, the art nouveau and the asbestos? Some do still troupe along the rows of mineral springs with their special drinking teapots, adamant that a 19th-century cure can solve 21st-century problems.

However, it is clear that many of the guests are in fact biding their time, kicking their heels among the genteel boredom of daytime in a decaying spa town and waiting for the evening to fall on the cupolas and colonnades. Karlovy Vary might not be able to clean up your liver, but it sure can launder your money.

The Russians have always had a soft spot for Karlovy Vary. It features in Anna Karenina and there is a longstanding Czech joke which has the ill-fated President Dubček inform Brezhnev in 1968 that if he insists on sending an invasion force to Prague, he will retaliate with a strike on Karlovy Vary. In the latter stages of the cold war, its proximity to the border with the west meant the resort crawled with the KGB. Those same agents came back, newly wealthy from the looting of Russian state assets in the 1990s, bringing a brashness to the faded halls and ballrooms.