Why are customer-service providers so rude to me?

It seems like every time I try to obtain help from a customer service provider, I am treated very rudely. I have been exiled from various locations (Taco Bell, 7-11, the corner grocery store on my street). I don't understand what I am doing to attract such a negative light. I think that it could have something to do with the fact that I'm not very sociable, and that I present an air of desperation (paying with change and what-not). Since when is change not a legitimate form of currency? I guess that people may just not like my face. Does anyone have theories about why I am the Charlie Brown of the customer service industry? Does anyone have helpful tips on how to play the role of customer in an appropriate way (because, honestly I'm really puzzled)?