Five guest houses and hotels in Banbury failed a child exploitation test carried out by Thames Valley Police and Cherwell District Council.
The objective of the operation, which also took place in Bicester, was to test the reaction of front of house staff when a man and girl attempt to book a room.
Twenty establishments were visited by Thames Valley Police during the operation.
Four of the eight hotels or guest houses visited in Bicester failed the test and were willing to rent a room overnight to a 15-year-old girl and a plain clothes police officer without checking the identification of either the girl or covert police officer.
In Banbury, five establishments failed the test, with six stating they were full or did not have staff available to make a booking. Only one establishment denied the couple a room.
Sgt Steve Willis of the Bicester Town Neighbourhood Policing Team said: “Child Sexual Exploitation (CSE) is an issue that Thames Valley Police takes very seriously. We feel it is very important to work with as many different organisations and individuals as possible so that more people can recognise the signs of potential exploitation. Raising awareness with our local hotels and guest houses about CSE can only lead to safer communities for our children.
“CSE can happen to any child, in any city, town or village, which is why Thames Valley Police and Cherwell District Council believe it is important to continue to educate and raise awareness. We want to support hoteliers so they can recognise the signs of CSE and prevent children becoming victims.
“Running operations like this allows us to practically test how local businesses react to a potential CSE and we can then use the results of such operations to help shape further staff training.
“We will work with the businesses that failed the test to ensure they check identification when an adult attempts to book a room with a child.
“It was pleasing to see that some hotel staff asked probing questions to our covert police officer and the girl, and then subsequently reported their concerns to the police. This is exactly what we want to see and they have set the benchmark that we want some of the others to now reach.”
Deputy police commander for Cherwell and West Oxfordshire local police area, Ch.Insp Emma Garside said: “The results of this test purchasing operation show valuable lessons are still to be learned. Our inability to book more hotel rooms was found to be more due to lack of availability rather than the actions of hotel staff.
“In every case where it is believed that a customer is seeking to obtain a hotel room for a person under 18 years of age, staff should ask for identification of all guests and contact police immediately with their concerns.
“There is a Hotel Watch scheme in place and these operations will continue to ensure the safety of those living and working in our area.”
Cllr Tony Ilott, lead member for public protection, said: “The safeguarding and protection of children is of the utmost importance, so it is vital that we carry out these checks and balances in order to ensure nothing is being missed.
“We all have a duty to keep a watching eye out for anything that we may think is suspicious, and I would encourage anyone who suspects that they may have seen something untoward, to be proactive in reporting any such incidents.”
The operation, which was carried out on February 2 and 3, was a follow up to tests undertaken on March 18 last year.