"Action is needed" at homes for the elderly run by Cornwall Care, after the company took its "eye off the ball", the Care Quality Commission (CQC) said.
The CQC previously rated the Penberthy home in Newquay as inadequate.
New reports highlight problems at three other homes run by Cornwall Care: Headlands in Carbis Bay, Trevern in Falmouth and Blackwood in Camborne.
Cornwall Care said it was rare for an inspection not to point out areas for improvement.
The CQC said Headlands was "unsafe" and overall "was not caring".
At Trevern "one person had not been able to have a bath or shower for eleven months due to the home not obtaining the appropriate bathing equipment to meet the person's needs," the report stated.
Action was also needed to address the "care and welfare of people who use services" and the "safety and suitability of premises," it was claimed.
The report on Blackwood said "people did not always have access to meaningful activities" and action was needed regarding the "safety and suitability of premises".
Due to changes in CQC reporting procedures the reports did not give an overall rating as it has done for Penberthy.
Adrian Hughes, the commission's deputy chief inspector of adult social care, said there had been "slippage" in services provided by Cornwall Care.
He said: "They have taken their eye off the ball in some aspects of that care."
A spokesman for Cornwall Care said: "We have worked closely with CQC and commissioners for many years and it is rare that an inspection of any care service does not point out areas for improvement.
"We welcome that feedback and always act quickly to make sure we are offering the best possible service to our clients."