The glass on the display cases should be cleaned several times a day as needed.
When the store is busy, or when there are kids in the store, they can be cleaned every 30 minutes.
The responsibility for cleaning the glass falls on the sales assistants, junior sales people and sales people in training.
If the store is packed with customers ANY staff member can take it upon themselves to clean the glass.
If any sales person is with a customer, and notices that the cases are dirty, they can ask ANY staff member to clean the glass and if they are free (not currently assisting customers) they should immediately clean the glass.