http://www.customerssuck.com/

where people in customer service go to complain about how the employees treat them.  Sounds like you have had an experience with clerks suck.  The racial composition of those involved may have had an influence as does gender and age.  Women have a hard time being waited on in hardware stores and young people usually have a hard time being waited on anywhere.  My guess is if you picked up antagonism, it was really there.

I also think you should be glad the clerk didn't follow the customer out to the parking lot and shoot him dead, as recently happened near Myrtle Beach SC .http://www.charlotte.com/breaking_news/story/156745.html