What do all the icons the customers show mean?

A green thumbs up icon means your customer was happy with their meal and service.

A seat icon means that there is no available seat in your restaurant.

A table icon with a plate on it means that the table the customer sat at needs to be cleared.

An empty table icon means your customer sat at a seat where there was no table available.

An icon showing a banana peel means that your restaurant has trash on the floor that you should clean up.

A red thumbs down icon means your customer was unhappy with the service. The icon that is shown prior to this will tell you more.

A clock icon means your service took too long.

A toilet icon means that your customers to do their "business"