Inspectors have been sent into two hospitals to carry out spot checks on their state of cleanliness.
Swansea's Morriston Hospital and Nevill Hall in Abergavenny, were given unannounced inspections on Tuesday.
The latter was the subject of a report in The Western Mail newspaper that purported to show undercover pictures of dirty walls and washbasins.
Health Minister Edwina Hart ordered the inspections with the intention of publishing the results.
The Western Mail said it took photographs of washing facilities at Nevill Hall's accident and emergency department which they said were in "a disgusting state".
It said the photographs clearly showed dirt and mould on ceramic washbasins, walls and doors smeared with dirt and grease and cracked or missing tiles.
The newspaper said the images were a "shocking indictment" of the "conditions in which the staff are expected to adhere to a strict regime of hygiene and cleanliness".
Inspectors were also unannounced at Swansea's Morriston Hospital
Ms Hart said she had ordered Tuesday's spot checks after reading the press articles with "dismay".
"I am passionate about the patient experience in hospitals and am determined to improve services for patients during my term in office," she said.
"A clean hospital environment must be an absolute priority and is essential for the health and well being of patients, staff and visitors.
"Cleaning services are a vital element in maintaining a healthy and safe hospital environment, which contributes significantly to the quality of patient care. I am determined that wards and facilities should be clean."
She added she would "ensure that those responsible for wards are given adequate control and resources to provide the quality of service that patients deserve".
Earlier this month Ms Hart said she was setting up a group of health professionals to consider enhancing and expanding the role of hospital ward sisters to have more power to improve ward cleanliness.
Gwent Healthcare Trust and Swansea NHS Trust said they welcomed independent checks on their performance.
In a statement, Gwent Healthcare Trust said: "We have invested heavily in infection control and results of a recent prevalence survey indicate that Nevill Hall Hospital has amongst the lowest infection rates in the UK."
Swanses NHS Trust director of nursing Liz Rix said the check lasted around three hours.
"Whilst acknowledging we are not perfect, all our staff are committed to continually raising hygiene standards," she said.