You were prompted to give a tip at an entirely self-service place whose employees couldn't bother to return your greeting?! I think you should receive a DISCOUNT on your food order in that case.

I have great sympathy for the underclass and underpaid in our society. In fact I am one of them. However teaching people that having a hand out and expecting others to give you money for absolutely nothing is not a good direction for our society to head in.

Table service is a challenging interpersonal and logistical dance that merits a tip, if anything does. Anything less than table service? Maybe not. Anyone who doubts this should try being a waiter.