Money changes behavior

Why does this happen?  I have two friends who turn into snobs every time we go to a restaurant.  They treat the waiter or waitress horribly!  I think their psyche says: "I am paying money, you are serving me...so, I am going to treat you however I want.  It drives me nuts!  I started to think about my own customers and how they treat me and I have to say, I am blessed with many good customers who treat me very well however, on occasion, I see this ugly attitude show up.  There is something that happens to people when they see themselves as paying customers, and their attitude changes.  Their behavior is different than what their friends and family see.  They figure they can treat someone anyway they want to as long as they are the customer.  My question to everybody reading this is: Is this OK behavior?  I don't think it is.  I do not think just because I am spending money somewhere it means I can treat someone like crap.  We all deserve respect and dignity.  When we deal with other people we give them that.  How is it when money is involved we throw all those principles out the window???  I have to admit...I don't get it!  Money should not influence the situation.  Being a customer means we get a service or product for a price, but it shouldn't change our behavior.  Who we are or how we act should be the same no matter if dollars are exchanged or not.  Why do I bring this up?  Watch yourself & your friends when you are in a store.  Is their behavior the same as usual?  If not,...why?  My personal thought is everybody deserves respect weather it's the girl making my coffee or the boy bagging my groceries .  As a customer, if I give this to someone who does not give it back to me....I will take my business somewhere else.  End of story.  Just because I am spending money however, does not give me the right to change my behavior.  What do you think?