Cherry. I tip those who do something above and beyond what they are paid to do. a Waiter is paid to bring the food to your table. If he does it with a lousy attitude and the social graces of a giraffe, I will not tip him. Same for a barber, taci driver or a camp counselor.
This summer in camp, we tipped one counselor and did not tip another. We simply had zero hakaras hatov to the counselor we gave nothihng to, because he did absolutely nothing for our son. The counselor was paid by the camp to show up every day, I dont have to tip him for doing so. The other counselor made it his business ot ensure all boys, including my son had a good time in camp, for that we are grateful and tipped him what we could.