Latest figures show an overall 3% rise in complaints to the regulator in the second half of last year compared to 2012, with two-thirds of the 1154 complaints being upheld.
If the trend continues, 2014 will be the third year in a row complaints have gone up.
The Care Inspectorate uncovered a widely varying range of good and bad practice across the care landscape in Scotland in over 5000 unannounced visits in the second half of 2013 by inspectors.
Three homes were among services criticised in November last year, with concerns including lack of treatment plans for undernourished residents.
It included Ainslie Manor in Girvan, South Ayrshire, where inspectors found staff had failed to intervene in cases of people suffering bed sores, and the site is closed to new admissions.
One elderly resident had lost 22lb in seven months after not being woken up at meal times.
At Torbrae House in Castlemilk, Glasgow, staff only had rudimentary knowledge of how to treat the malnourished.
Staff had to be taught how to notice when residents were at risk of dehydration.
The Knowesouth Care Centre near Jedburgh in the Borders was so short-staffed an enforcement order against the owner required an immediate increase in the number of workers caring for up to 50 older people.
Staff needed training in critical aspects of nursing such as "nutrition, dementia care, medication management, moving and handling and challenging behaviour".
The inspectorate update follows a police investigation being launched into deaths of residents at the Pentland Hill Care Home in Edinburgh.
Inspectors have also publishing worrying reports on two other care homes in the city including one run by Edinburgh City Council
Gilmerton Care home and the council's Ford Road Care Home were both heavily criticised and closed to new admissions.
The Care Inspectorate has been increasing the number of its inspections and moving to halt often serious failures since it was upgraded in its regulatory role taking over from the Care Commission three years ago.
Chief executive Annette Bruton said: "Most care services in Scotland perform well, but we do not hesitate to take action where necessary. Complaints are a very important part of our work.
"If we investigate and uphold a complaint, we generally require changes which have a big impact on people's lives. Crucially, we use the intelligence we get from complaints to plan our inspections."
"If a care service has an unusual pattern of complaints, we know straight away that something needs to be looked at and can bring forward an inspection or make it even more intense."
Ainslie Manor owner Brian Sage said he is "confident that 90% of the complaints against us will have been rectified in three months".
A spokesperson for Torbrae said: "Everyone is working extremely hard to address the issues raised by the Care Inspectorate and we are determined to take any actions necessary to achieve this."
A spokesman for Knowesouth, which is run by St Philip's Care Home, said: "We have a detailed action plan in place to address these issues." The company was "committed to ensuring that [the] improvement notice is met."
The Care Inspectorate regulates a wide range of care services including nursing agencies and fostering services. From April to December 559 complaints directly relating to care homes were received by the inspectorate with 65% being upheld.