Hygiene inspectors on an unannounced visit spotted five doctors, nurses and a volunteer breaking guidelines on cleanliness when dealing with patients at the Vale of Leven Hospital in West Dunbartonshire.
Dirt was also found in the physiotherapy department, according to the report published by the Healthcare Environment Inspectorate (HEI) yesterday.
An inquiry into an outbreak of Clostridium difficile (C.diff) which killed 18 people between December 2007 and June 2008 is ongoing.
The inspectors, who visited last month, found the majority of the hospital was clean, tidy and uncluttered. However, in the physiotherapy department they noted treatment couches were dirty underneath, curtain rails were dirty and there were grubby finger marks on the wall of the equipment store.
They spotted the hand washing breaches on three wards.
The report said: "NHS Greater Glasgow and Clyde must ensure all staff and volunteers comply at all times with national guidance relating to hand hygiene.
"This will reduce the risk of infections and cross contamination for patients and the public."
Susan Brimelow, HEI chief inspector, said she expected the issues identified to be addressed "as a matter of priority".
Rory Farrelly, NHS GGC's acute division director of nursing, said: "We are pleased that overall we are complying with the majority of standards.
"In particular, the inspector highlighted infection prevention and control was well promoted in all areas and communication between ward staff, infection control, domestic services and estates staff was good. However, we are extremely disappointed that inspectors found staff not complying with our hand hygiene policy.
"This is clearly unacceptable and we will be reinforcing to all staff, particularly medical staff, the need to adhere to strict hand hygiene policy at all times."
An action plan to deal with all the recommendations is being implemented.
Patrick McGuire, partner at Thompsons Solicitors and lawyer for the victims of the hospital's C.diff outbreak, said: "It's utterly shocking that the report shows lessons still aren't being learned from the tragedy at the Vale of Leven, where families saw their loved ones go into hospital and never come home.
"This is a very serious public health issue. Fundamental errors and oversights such as non-compliance with hand hygiene can have fatal consequences.
"The public inquiry into the outbreak of C.diff at the Vale of Leven gives rise to clear concerns over the quality of care given to patients there, but there's a larger issue – the whole NHS approach to care must be put under the microscope to make sure this doesn't happen again."