Final answer:
The frequency of checking dishwashing machine cleanliness varies, but commercial establishments often conduct daily or per-use inspections. Routine maintenance is also advised to ensure proper hygienic standards are met, and special care must be taken with materials incompatible with dishwasher detergents.
Step-by-step explanation:
The cleanliness of dishwashing machines should be checked frequently to ensure the highest standard of hygiene and to prevent the spread of foodborne diseases. There isn't a one-size-fits-all rule for the frequency of these checks as it can depend on the volume of use and the types of items being washed. However, establishments that use dishwashers for commercial purposes often adhere to daily or even per-use inspections for any residues or food particles. Also, routine maintenance checks are recommended to monitor for the growth of biofilms or any other cleanliness issues that may compromise the effectiveness of the dishwasher. Special care should be taken with certain materials such as silver, brass, cast iron, bronze, pewter, and gold leaf as most dishwasher detergents are incompatible with these materials.