The use of sniffer dogs at Manchester Airport has been criticised after dogs there failed to discover any Class A drugs in a seven-month period.
But one dog, trained to detect illegal animal products, often found "small amounts of cheese or sausages" carried by holidaymakers, a report said.
The review, by the Independent Chief Inspector of Borders and Immigration, assessed border checks at the airport.
The Home Office, which oversees border checks, said improvements must be made.
Some recommendations had already been implemented, it added.
The report examined how "efficiently and effectively" Border Force - which is managed by the Home Office - operated at Manchester Airport.
The airport, the UK's third largest, has six detector dogs and new kennels, which cost £1.25m.
Inspectors said that although heroin and cocaine were assessed as "very high priority" for the search team, no Class A drugs had been found by the dogs between November 2014 and June 2015.
As a result, the report concluded that "Class A drugs detections were not at the level that might be expected", and said Border Force should review "how particular flights were risk assessed" and where staff and dogs were deployed.
The amount of goods seized by dog units represented a "low return on investment", the report added.
'Lack of innovation'
One dog, which had been trained to sniff out smuggled animal products, had detected many items accurately - but the report said most were "small amounts of cheese or sausages, wrongly brought back by returning British holidaymakers and posing minimal risk to UK public health".
This "accurate detection" meant the dog found animal products. It was then up to its handler to decide whether any action should be taken.
Travellers arriving in the UK from EU countries can bring fresh food including meat and dairy products, but there are strict rules about food brought from non-EU countries - including a ban on all meat, dairy and potatoes.
Inspectors said it would be of "more strategic value" to target flights where the dog might find bush-meat - which could pose a considerable threat to public health.
"A senior manager agreed that there was a lack of innovation in the use of the dogs, and told us that a new management structure was being put into place to take a fresh look at their deployment," the report said.
Over the period however, the dogs had helped in the seizure of more than 46,000 cigarettes, 60kg of tobacco, 181kg of illegal meat and £28,000 cash, the report said.
Other elements of border checks were also reviewed, with the report finding that:
- A "significant number" of Border Force staff at the airport were not fully trained in immigration work, leading to "delays and inefficiencies in the processing of passengers".
- Some staff were called upon to supervise immigration functions at a terminal for a shift "without the relevant immigration knowledge or training".
- There was a "control breach" in April 2015 when passengers from a delayed flight were "misdirected through an unmanned immigration control". Managers "acted decisively" to deal with the breach.
Elsewhere, it praised Border Force's work in areas including the safeguarding of children, and said the force was "actively involved" in tackling issues such as human trafficking.
A Home Office spokesman said inspectors recognised staff at the airport were conducting "all required checks at passport control".
"However, we acknowledge that further improvements need to be made. We welcome the report's findings and accept all the recommendations - many of which, including a new recruitment and training programme, are already being implemented," the spokesman added.
A Manchester Airport spokesman said staff "work extremely closely" with Border Force and "support their work to address the issues raised in this report".