Care homes with five-star ratings are receiving premium fees despite not meeting essential standards set out by the care regulator.
Local authorities pay higher fees to care homes awarded top ratings.
But critics say this is a "cheque book system" open to any home prepared to pay for a rating.
The Care Quality Commission advises people to visit homes and check their most recent CQC inspection report before making a decision on care.
Care regulator the Care Quality Commission (CQC) stopped issuing its own star ratings in 2010 and now some homes pay independent ratings companies and consultants to assess them instead.
Gwenda Dunn was surprised to find that her aunt's care home had been awarded five stars by such a company.
"This is not a complaint against the home - it's a complaint as to how the home could be given five stars when it patently was not," she told the BBC's 5 live Investigates.
5 star failures
Mrs Dunn says her aunt's room was often cold and calls from her aunt for a commode during the night were sometimes ignored by staff.
Also, her aunt was frequently disturbed by another patient with dementia who often entered her room uninvited.
"I was there when the inspection was done. I spoke to the inspector and raised a fair amount of issues and then we found out within a week that the home had got five stars again," says Mrs Dunn.
"People who aren't in the know would take it as face value, not recognising the reality."
The home was rated by David Allen, an independent consultant who trades under Prestige Quality Ratings (PQR).
Mr Allen says the issues raised with him lacked substance and were misplaced. He also says other people at the home spoke very highly of the care provided and he saw no reason to downgrade the home.
PQR is one of three independent ratings companies recognised by Sefton Council. The others are RDB Star Rating Limited and Assured Care.
With the top five-star rating attached, families might believe a home is providing an outstanding level of care.
But the BBC has found that out of 80 homes given a four or five-star rating in the Sefton area, 14 are failing to meet one or more of the essential standards set out by the CQC.
This includes standards of staffing, standards of treating people with respect and standards of caring for people safely and protecting them from harm.
All of the homes had been rated by either RDB Star Rating, Assured Care or PQR.
The CQC is taking action against two of the highly-rated homes, demanding immediate improvements be made - although it is not known which company provided their rating.
All three ratings companies have defended their awards system.
"I always take account of what the CQC have to say... but the CQC doesn't have to be right every time," says Frank Watts of Assured Care.
David Allen of PQR insists that his company's ratings are "accurate reflections of the quality of the care provided at care homes at the time of the assessment".
RDB Star Rating told the BBC its assessments were "comprehensive and reliable".
Higher fees for homes
Sefton Council pays a quality premium to homes given a high rating by the companies - a residential or nursing home with five stars receives an additional £40 per week on top of the basic fee paid for each person in its care.
A spokesman for Sefton Council said: "All the companies providing quality ratings use assessment criteria linked to outcomes in care home provision.
"We work closely with the CQC to ensure quality standards are closely monitored. If either party feel standards have reduced, through their own monitoring activity or inspections, we will decline or even suspend a particular rating and work with CQC in relation to this."
Sefton council is not the only one to pay a quality premium to homes awarded a four or five-star rating.
Redcar and Cleveland Borough Council says that since it introduced the RDB rating scheme in 2001, standards of care homes across the borough have improved.
But the BBC has learned that a quarter of its highly rated homes are failing to meet all the essential standards set out by the CQC.
"The council does feel that a new quality assessment tool would help to continue the drive to improve the quality of provision and therefore the RDB scheme will cease to be used at the end of this financial year," a council spokesperson said.
While the old Care Quality Commission rating system did have problems, critics say it was at least a system which was nationally recognised, independent, and easy for the public to understand.
"We maintain it is the responsibility of CQC as the regulator to assess the quality of care homes," says Nadra Ahmed, chair of the National Care Association which represents care homes.
"When the star rating system was scrapped by the CQC they consulted on the introduction of a system whereby assessments would be carried out by organisations independent of the CQC, which would be selected through a tendering process.
"The process was voluntary, so providers would pay to be assessed. The National Care Association felt strongly that this would be a cheque book rating system which enabled those who could afford it, to purchase a rating."
Bupa, the UK's second-largest care home group, is also critical of the CQC for abolishing its rating system:
"We would like to see them [star ratings] back so people can identify excellent care homes," said a company spokesperson.
"Other organisations, such as local councils and independent companies, are creating their own systems - but this could be confusing because there is no consistency."
The CQC warns people not to rely on ratings from outside companies when choosing a home.
"We do not endorse any external ratings systems," CQC operations director Amanda Sherlock told the BBC.
"We would recommend people look at a range of information including our website to get the latest reports into care homes, nursing homes, hospitals and other care providers."