London - Sex, drugs and rock 'n' roll - nothing new for the hospitality industry but British hoteliers say loud music, used condoms and alcohol could hint at something darker: modern-day slavery.
Add last-minute bookings, paying in cash or landing without luggage - all are warning signs that human traffickers could be using the cover of hotel life to hold, abuse and sell victims.
Yet for hotel bosses - this is just the tip of the iceberg.
For modern slavery poses a triple threat to the hospitality industry, from people being sexually exploited in hotel rooms to goods made via global supply chains that are tainted by forced labour and sub-contracted workers at risk of coercion and abuse.
Many hotels in Britain are teaching staff to spot the signs, and scrutinising suppliers of goods from shampoo to sheets.
But exploitation of their employees is the insidious threat. Countless hotels are in the dark about the backgrounds of their workforce - and may be inadvertently hiring slaves, experts say.
"Outsourced staff are a key risk in supply chains in the hospitality industry when it comes to modern slavery," said Dominic Fitzgerald, development director at Shiva Hotels group.
"Unfortunately, responding to modern slavery is not something that is driven hard enough within the industry - there is no legal requirement," he told the Thomson Reuters Foundation in a plush bar at a Hilton hotel near London's Heathrow Airport.
Many major hotels in Britain hand control of their workforce to recruitment agencies - leaving mainly low-skilled and migrant workers vulnerable to debt bondage, poor pay and long hours, and working under duress to fill the pockets of their traffickers.
The hospitality sector employs at least 3.2 million people in a country estimated by rights group Walk Free Foundation to be home to 136,000 slaves - with the crime growing and evolving.
But many industry firms focus on the source of their goods rather than their staff - either unaware of the risk of abuse or unwilling to pay more to address the threat, according to Andrew Crane, an academic at Bath University and labour issues expert.
"To prevent the misery of modern slavery from blighting our workforces ... companies need to be able to trace the origin of their employees in the same way as most can for their products."
LESS TALK, MORE ACTION
Hospitality is one of Britain's top employers and fastest growing sectors, worth 130 billion pounds ($172 billion) and set to create 500 000-plus new jobs by 2021, the trade body says.
Traffickers are already deeply embedded, and an estimated 93,000 people are sexually exploited in hotels across Europe each year, according to a study funded by the European Union.
A gang member who trafficked 19 Asian women to Britain and sold them for sex in hotels in a dozen cities was jailed in 2017 for four years in a case police and prosecutors said exploited the hospitality sector in an "organised operation".
But several big players have joined forces to fight back.
The Stop Slavery Hotel Industry Network was founded in 2016 by the Shiva Foundation - an anti-trafficking group funded by Shiva Hotels - to boost ethical recruitment and root out abuse, promote responsible supply chains and tackle sex trafficking.
Thousands of hotel staff in Britain - from cooks to cleaners - are being trained to identify possible trafficking signals, such as excess alcohol in a room, or a child staying over.
Yet too few hotels - big or small - are doing enough to ensure their own workers are safe from exploitation, said Martin Birch, head of WGC, an outsourced cleaning services provider.
"Modern slavery has become a hot topic, but hotels need to go a lot further," said Birch, who employs about 5,000 staff.
His workers are sometimes nervous on first joining, having suffered abuse from former bosses, seen their pay withheld or deducted, and faced threats of eviction from staff quarters.
So WGC pairs new hires with older staff for reassurance, offers a helpline for staff to report complaints, and once even saved a worker from the clutches of traffickers, Birch said.
With many firms paying lip service to the threat ahead of Anti-Slavery Day on Oct. 18, Birch urged concrete action.
"(Modern slavery) is not another health and safety type of heading. It needs to be eradicated ... not just spoken about."
SUSTAINABILITY TO SLAVERY
Insiders say some hotels are knowingly passing the buck.
"Hotels must stop hiding behind contracts - they should have direct contact with all workers rather than absolving themselves of responsibility," said Peter McAllister of the Ethical Trading Initiative, a group of trade unions, companies and charities.
"It is primarily a question of political will and money – and legal liability in some cases," the chief executive said.
An ongoing review into the 2015 Modern Slavery Act - which requires firms with a turnover of at least 36 million pounds to report on their anti-slavery efforts - could see the law strengthened and force companies to do more, he added.
Hotel bosses said sustainability had been the sector's watchword in recent years - from sourcing organic produce to encouraging guests to reuse towels to help the environment - and that slavery now deserved similar scrutiny and robust action.
"It used to be the case that hotel chefs could tell you the name of the cow behind the piece of beef on your plate, but not the names of the housekeeping team," said Fitzgerald of Shiva.
"Yet that is changing."
The industry is also mulling how Brexit - Britain's planned 2019 departure from the European Union - and the rise of short-term home rental companies like AirBnB may affect worker rights and abuses, as well as sex trafficking in hospitality, he added.
For 20-year-old Theodore Melbourne, a part-time cleaner with WGC who works at a Hilton when not at university, such concerns are beyond him as he goes about his daily housekeeping routine.
After being misled and underpaid at another hotel, he is simply content to have an employer who treats him with respect.
"The job is great - it is a friendly, positive environment," he said while making up a hotel bed. "It just feels right here."
* Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org