Some cosmetic surgery clinics are using aggressive marketing and putting sales before patient safety, according to consumer group Which?.
Breast augmentation is the most popular cosmetic procedure
Undercover researchers at 19 clinics found the risks of procedures were often played down during sales pitches.
Some of the clinics described invasive surgery as "scarless" or "minor procedure", said Which?, which wants tighter regulation of the industry.
The government said the public needed to be aware of the risks.
Which? sent undercover researchers, who recorded their consultations using hidden audio equipment, to chains and local clinics in London, Manchester, Leeds, Nottingham, Birmingham, Leicester, Cardiff and Bristol last summer.
These included visits for possible liposuction, breast augmentation and Botox treatment.
None of the clinics visited gave all the verbal and written information they should have, according to Which?
In some, non-medical staff gave inappropriate and inaccurate advice.
And many outlets used pressure selling to try to rush people into surgery, such as offering discounts, buy-one-get-one-free offers or setting deadlines, it said.
Which? said one sales assistant had showed her breasts to a researcher in order to try to secure a "boob job" sale.
Industry guidelines say patients should have a two-week cooling off period after booking procedures and they ban the use of time-limited financial inducements.
Which? spokeswoman Jenny Driscoll said: "There are risks with all cosmetic treatments, so when people go for a consultation they should get accurate and in-depth advice from a medical professional, not a pitch from an unqualified salesperson.
"The Health and Social Care Bill is currently going through Parliament and Which? will be calling for the government to make sure that regulation of this industry is more robust."
Douglas McGeorge, president of the British Association of Aesthetic Plastic Surgeons, said clinics were "abusing" the fact the public did not take enough time to assess treatments.
"People seem to spend more time choosing a new TV than weighing up whether they should have a cosmetic procedure," he said.
Hamish Laing, of the British Association of Plastic, Reconstructive and Aesthetic Surgeons, said: "The Which? report shows the need for better policing of cosmetic treatments and we are concerned that patients are not being given the quality of information they need.
"Anyone considering plastic surgery should ensure that they are getting as much accurate information as possible on what the procedure entails, what the potential risks could be as well as what aftercare they will receive.
"It is unacceptable that some patients are not getting this information as a matter of course, or even being given the wrong advice."
A Department of Health spokesman said there were laws applying to cosmetic procedures and it had asked the independent healthcare advisory services to establish a regulatory regime for them.
"It is vital that the public also inform themselves fully of the potential risks and consequences of such treatments.
"People undertake these cosmetic procedures by choice, privately. They are not provided by the NHS.
"There is a balance to be struck as to how far the taxpayer should be expected to pay for the regulation and policing of the regulation for such procedures."