Plain clothes officers have visited hotels across Yorkshire and the Humber as part of ongoing efforts to stop child sexual exploitation.
At each location, an officer was joined by a child as they tried to pay for a double room in cash and without any identification.
They visited hostels and other licensed accommodation providers in Bradford, Huddersfield, Leeds, York, Scarborough, Scunthorpe and Hull.
The operation followed delivery of a training package to hotels and licensed premises across the region, which aimed to highlight key warning signs of exploitation.
Police said today that 63 instances of children being abused in hotels or bed and breakfast accommodation were reported to the region's four police forces during 2015 and 2016, although 10 of these were said to have taken place outside Yorkshire and the Humber.
It prompted the training, delivered with support from safeguarding charities, which included tips on how to spot the warning signs of potential sex offenders and what hotel staff should do if they have concerns.
Detective Superintendent Simon Beldon, of the Yorkshire and the Humber region, said: "The purpose of this operation was not to stigmatise hotels but to see if the training is working and having the necessary impact.
"I am pleased that the vast majority of establishments passed the test, although slightly disappointed that most only turned the officer and child away rather than actually report them to us. Only three establishments did do that."
Three hotels in Bradford, Leeds and Scunthorpe recognised all of the signs of exploitation, refused to allow the room to be booked and contacted the police to give information that would have assisted them in safeguarding the child.
Det Supt Beldon said: "The training package encourages members of staff working in these establishments to be professionally inquisitive in situations that don’t look or feel normal.
"Staff at hotels that have done this in the past and reported it to the police, have undoubtedly prevented children coming to significant harm."
The Independent Inquiry into Child Sexual Exploitation in Rotherham, which shared its findings in August 2014, highlighted the issue of hotels being used by people who were sexually exploiting children in the town between 1997 and 2013.
It also detailed how training of hotel managers in the town had resulted in one perpetrator being caught with two under-age girls by South Yorkshire Police.
A separate review of child sexual exploitation services in Rotherham, published by children's charity Barnardo's in 2013, had suggested working with hotels and B&Bs, taxis and public transport, and other venues to identify potential offenders and prevent further opportunities for abuse.
Det Supt Beldon said: "Safeguarding children is everyone’s business. The police cannot and must not work in isolation.
"We can only stop those who seek to sexually exploit children if everyone acts as our eyes and ears. If something feels wrong, like a child going to a hotel with a much older man, then let us know."
Craig Darwell had been told it was the only room available when he booked almost three month in advance and paid by credit card, and did not have any ID with him when he checked in.
The hotel chain later apologised to Mr Darwell for the distress caused but said it took its responsibilities towards protecting children and vulnerable young people extremely seriously.