Answer:
Every time they are dirty.
Explanation:
If you don't change the towels out for the sandwich station every time they get dirty, it can lead to some food born illnesses that you can potentially give customers. If a customer gets a FBI, you can lose a customer, or get sued. It is always best to change them every time they are visibly dirty to prevent accidents like FBIs from happening.
A thing that is or is likely to be wrongly perceived or interpreted by the senses.
A deceptive appearance or impression.
A false idea or belief.
If you mean they should actually be a part of it with them in it, no. but if you mean interacting with them like questions, then yes! hope i could help =)
