I worked for a while for a major high street music retailer. Just pricing stock and standing at the checkout. Nothing major, and I was in my early 20's.
We used to get literally 1000 or more applicants at Christmas or the Summer Holidays for 4 positions. An advert was posted in the window and in the local free papers, and people would come to the front checkout and ask for an application form.
We would wright A, B or C in the top RH corner of the application form and give it to them, based upon the first impression that the staff member had of the individual asking for the form. A form that was returned with a C on it was binned. The other two were sorted into A's and B's.
Bottom line is, right from the get go, the very first interaction, you are being judged. The company's opinion was, if their existing staff didn't find you presentable or immediately likeable, the odds were high the buying public would not do so either, so you are no good as forward facing staff. Harsh, but real life is harsh, and it is often better not to confront people with the harsh realities of life that face a petulant outburst in front of customers on the shop floor because someone had their fragile ego bruised.