In the first wholesale review of the consumer protection system for 30 years, the National Audit Office and Audit Commission will jointly state that "rip off" Britain has been allowed to prosper under the current toothless regime.
There are also fears that too many unsafe products such as children's toys and food are still widely available; that unscrupulous estate agents are able to operate with impunity; and that it is too easy to give consumers short measures.
The report, to be published on Wednesday and called "Protecting the Consumer from Unfair Trading Practices", is expected to question whether the Office of Fair Trading and the 1,800 trading standards officers working across the country are providing value for money.
One problem likely to be highlighted is the lack of co-operation between jurisdictions - as officers report exclusively to their local authorities - and between local officers and the OFT at the national level. It is also thought likely to question why some local authorities spend so much more than others without necessarily providing better consumer protection.
Recently published figures showed that expenditure ranged from pounds 3.85 per head of population in Shropshire down to pounds 1.74 in Hertfordshire.
Despite the Government's promises to fight "rip-off Britain", several counties have cut their spending on consumer protection in recent years.
However, Wednesday's report is expected to warn against any further financial pressures on recruitment or training which could only further weaken consumer protection.
The OFT, set up in 1973, is responsible for identifying and tackling unfair trading practices nationally. But the report is expected to highlight the fact that - despite its recently completed high-profile investigations into price rigging by supermarkets and car manufacturers, now before the Competition Commissioner - the OFT is often hindered from taking forthright action against persistent wrongdoers even when the case against them is proved.
Under existing laws, the Director-General of Fair Trading, John Bridgeman, has to go through a lengthy process of seeking assurances from traders about their future conduct before he can take legal action.
Frequently, traders take advantage of this weakness in the law to spin out the process almost indefinitely - a fact that Mr Bridgeman has repeatedly pointed out in a bid for a change in the law.
The report, an unusual joint production by the two highly influential watchdogs, is also expected to call on both the OFT and trading standards officers to be more responsive to public concerns.