Most Helpful Girl
At my workplace, there are two uniforms: Manager (Tucked in polo shirt and black or khaki pants) and Associate (Same as manager, but add an apron and a hat). Sometimes, I don't wear the apron and hat because the manager on duty is very lax about it and I always get so much more respect from customers (note that my workplace is located in a classy hotel, so often we have very stuck up and rude customers). So yes, I do think that how you're treated depends on appearance, unfortunately. I think it's like 60 percent appearance and 40 percent attitude (level of confidence and such).
Here's another example if you feel like reading: When I got to Target, I don't really worry about how I look, so I often just go in sweats and no makeup with my hair in a bun. When I'm checking out, the employee is usually pretty monotoned with me. But whenever I stop to pick up something on the way home from going out, (so I'm dressed nicely and all done up and everything) the employees are always much happier around me and such.