Young people were able to use gaming machines in every licensed premises they entered as part of an underage and undercover exercise in Carmarthenshire.
The supervised volunteers were under 18 and therefore should not have been allowed to use the machines.
The exercise at 17 licensed premises and members' clubs has prompted the county council to recommend changes to its gambling policy.
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Cabinet members have approved the amendments, including a statement strongly advising operators to improve staff training and the supervision of gaming machines.
The report before cabinet contained brief details about the underage exercise, and said a public consultation had been carried out about Carmarthenshire's gambling policy. Such policies have to be reviewed every three years.
There were 86 consultation responses from residents, businesses and licence holders. Some said the sector was well run in Carmarthenshire, while others said problems stemmed from the rise in online gambling.
One respondent said: "Keep your noses out of people's lives. Got nothing to do with you."
Some felt there were too many betting shops in town centres, while another said schools should do a session on problem gambling. The consultation and review found that overall there was no clear evidence that specific areas of Carmarthenshire had gambling-related problems, while noting the underage test exercise.
Speaking at the cabinet meeting, Cllr Glynog Davies said the education department was looking into sessions at schools to give out gambling-related advice.
Cabinet colleagues felt there was too much gambling advertising.
Council leader Emlyn Dole said: "It (advertising) is in your face, and it is damaging."
The gambling policy amendments will be considered by full council on March 9.
The UK Government is due to publish a white paper on the future of the 2005 Gambling Act. The Local Government Association (LGA) and Association of Police and Crime Commissioners want tougher powers for councils to determine where and how many gambling premises can open in their areas, plus a clampdown on the volume of gambling advertising.
The LGA said evidence showed that gambling and betting premises were typically located in more deprived areas, where residents might be more vulnerable to gambling harm.
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