The Broadcasting Standards Authority (BSA) wants people who are filmed for reality television shows to be informed of their rights.
Research commissioned by the authority found some programmes leave people confused about where they can be caught on camera and when the footage can be used.
The study looked at three reality programmes - Piha Rescue, Coastwatch and the consumer show Target.
The report cites the case of a tradesman found to have acted inappropriately while carrying out a job on Target's test property.
The man told the researchers the broadcast of the hidden camera footage and his subsequent job loss devastated his wife and led his family members to believe he was morally deficient.
The researchers say Target should have told the man he was going to feature on the show but executive producer Vincent Burke says the programme is within with its rights to use hidden cameras.
"The privacy issues are not necessarily straightforward but in the case of Target we are very clear about what we film and how we film it and why we film it."
He said he was surprised that people had not realised they could be filmed in public places, and says more education may be needed.
The BSA's outgoing chief executive, Dominic Sheehan, says it can be traumatic for people to see themselves on television when they didn't know they had been filmed.
He says people who might be included in shows could be given a leaflet which states their rights and those of the broadcaster.
Privacy lawyer Kathryn Dalziel says programmes can film in public places and show the footage as long as they don't give away personal facts about the individual, however she would like to see programmes getting consent from their subjects.