No, a service is just making sure that the car is safe to drive, right? That's what I always think about it anyway, but you're right, people do tend to get the wrong ideas about things like that. You should let them know exactly what's included before they leave their car with them, and more to the point let them know what isn't included then they're not going to be disappointed.
Yes it has to make sure that everything is in order. Certainly not anything to do with the way that the car looks. We have started making a list of all of the marks on the car before the owner leaves it, because you would be surprised at the number of people who decide to try to blame us for things that we haven't done to their vehicle. Very dishonest.