Why it is important to be polite with customer?

How often have you been to a store and not being sure if you wanted to really buy something. I you meet a nice seller, who is smiling and really attuned to your needs without trying to pressure or rush you, you are more likely to purchase an item. Not because you really needed that piece of merchandise, but just because you wanted to maintain that Excellent starting relationship with the seller. Why is that? This is just because we are social beings. Everything that goes in that social bonding direction make us feel safe and good. Nobody would like to purchase something from their worst enemy. He might sell you garbage and tell you, it's diamond. In reverse, we feel safe and comfortable when we are buying from a smiling, polite associate.