You may ask the Definition of Guest or What Is Guest or who is the Guest ?
What is Guest / Definition of Guest :
In the F&B section Guest is a person who presents him/her self to a certain establishment to Buy, Eat or Drink anything and he must be fit to be accepted by the establishment.
We can say another definition of guest easy way that: If anybody come to you or come to your restaurant to buy something or to have anything he/she is your guest in F&B Department or F&B Section.
If he/she don’t take anything then he/she is your guest because he/she may not take anything right now but if you think the she/he not your guest and you make misbehave with him/her then just keep in your mind that he/she never come back to you to have anything. When a Guest come on your home I think He/ she don’t buy anything form you but here in your restaurant a guest may buy anything form you but if she/ he don’t buy then you can not ignore that he/ she not your guest.
So, if she/he does not take right now its okay he/she will take latter or next time sure.