IT’S a sun-soaked slice of paradise by day, a sleazy den of sin by night.

After dark, thousands of tourists fill the seedy clubs and pleasure dens of Pattaya, Thailand’s most notorious red-light district, and arguably the sex capital of the world.

Pattaya’s X-rated reputation is nothing new — the local sex industry and its popularity with foreigners goes back decades — but despite tough laws and recent government crackdowns, it seems to be bigger and bolder than ever.

Overnight, Australian men were among 11 foreign tourists arrested along with 14 sex workers during a raid on an illegal orgy at a Pattaya hotel.

Stunning footage from the raid on the Tulip Hotel shows the sweaty, semi-naked, middle-aged men — who had reportedly paid about $62 to take part in the orgy — trying to cover their faces with towels as they are rounded up by Thai police.

Police allegedly arrived to find people having group sex in the hotel room that was scattered with condoms, lubricant, sexual enhancement drugs and toys.

The tourists reportedly came from Australia, America, Britain, Canada, China, Malaysia, Singapore, Germany, Thailand, Cambodia, India and Ukraine. The hotel’s Chinese owner was arrested on suspicion of running a hotel without a licence and hosting obscene events.

In line with values of its deeply conservative society, prostitution is illegal in Thailand. It’s illegal to work as a prostitute, it’s illegal to make money from prostitution, and it’s illegal to own a venue where prostitution occurs. Fully nude entertainment is also banned.

But Thailand is said to have around 123,000 sex workers, who contribute up to 10 per cent of the country’s GDP. And about 27,000 of those sex workers are based in Pattaya.

Most of them can be found on Pattaya’s infamous Walking Street, a 2km strip lined with go-go bars, pleasure dens and ping-pong shows.

“Pattaya central looks a bit like a very naughty Noosa or a rather horny Hervey Bay. Rather than retired couples, hundreds of — usually extremely overweight — older white Western men walk around with young Thai girlfriends,” journalist Luke Williams wrote for news.com.au of his experience in Pattaya.

“There’s lots of white men here — about 100,000 of us, or one to every three Thais. There’s also white sand, luxury white condos, teeth whitening dentists everywhere, make-up adverts promising to whiten Thai girls’ skin, and Thai money-boys wearing that same face-whitening foundation — as they squeak ‘massage sir?’ while making open-mouth, blow job gestures to every male who walks past.”

Human rights groups have long been concerned about exploitation and human trafficking in Thailand’s sex industry, which is said to date back to the Korean and Vietnam wars, when foreign troops would be stationed nearby.

But for years authorities appeared to do little about it, and Pattaya’s reputation for lawlessness grew stronger — until Thailand’s first female tourism minister announced everything would change.

Kobkarn Wattanavrangkul vowed to shut down Pattaya’s sex industry, and do away with its world famous ladyboys, go-go dancers and ping-pong shows, when she announced a crackdown in 2016.

“Tourists don’t come to Thailand for such a thing,” she said.

“They come here for our beautiful culture. We want Thailand to be about quality tourism. We want the sex industry gone.”

What followed was months of late-night raids and mass arrests in brothels and clubs across Pattaya, with Western tourists among those bailed up by police. Officers also stormed pubs and clubs, seizing drugs and tobacco and drug testing patrons.

While the crackdown settled things down for a while, residents said Pattaya was well and truly back to its own tricks — and may have become worse.

The city has seen a spike in violent crime over the past 12 months, including violent brawls between tourists.

In February, Melbourne man Benjamin Robb was brutally bashed to death at the Ruby Club, a licensed venue in Pattaya’s notorious Soi 6 laneway.

His alleged attacker, American man Jose Manuel Polanco, claimed he attacked Mr Robb in self-defence after seeing the Australian strangle a sex worker.

Days later, a massive brawl broke out on Walking Street between British tourists and men of Middle Eastern appearance.

Meanwhile, the sex industry has continued to thrive despite the crackdowns.

Businesses have found a loophole to avoid prosecution for prostitution: they hire sex workers in the bars to talk to patrons, but offer a “bar fine” of about 500 baht, or $20, which lets the patron secure private time with the worker to strike up a deal for sex.

Operators have also found ways to move the sex trade offshore. Earlier this month, German authorities raided 62 properties and arrested seven men they allege brought Thai sex workers to Germany on fake tourist visas.

British journalist Andrew Drummond, who specialises in crime in Thailand, said the other challenge to shutting down the sex trade was that it was a lucrative business for many facets of Pattaya society — from the sex workers, who often relied on earnings to support their families, to hotels, taxis, the mafia and, according to accusations, police.

He said the system was known as “pon prayote”.

“It means everyone benefits,” Drummond said. “It brings in massive amounts of money and simply couldn’t happen without police connivance.”