People in the service industry love to give that look. it's the only way that they can safely extract revenge upon the public that makes their job and lives unpleasant. doesn't matter who you are, what you buy, or even whether or not the person expressing that scorn is a better person than you are; a "businessman" from the local area gave me "the look" at a meeting and he is now on trial on a 6 million dollar tax evasion charge.
picture this scenario. I'm a dropout who got a ged. I'm drug free, most of the time, and drink every night. I have hit most of my girlfriends and my only soon to be ex wife. I steal food off of the shelves at night, and once in a while, shortchange my cash customers if they look really stupid. I want to go take a leak, and in you walk and you fool around making yourself a cup of coffee. When you finally drag your worthless butt to the cash register, you ask for a penthouse.
What am I, a model citizen going to do? I'm going to get my ounce of flesh. I'm going to give you the most pecker withering glare I'm capable of, and follow it with a snarky "have a real nice evening, now, ya hear? Enjoy yourself." Then, I'm going to pat myself on the back for having ruined your night, and fantasize that you're going to go home and either cry or commit suicide.
Inadequate people like to hurt other people. Any way to do it is just hunky dory, and if they have a reason to dislike you (you have guns) they will work out some way to make you unhappy (like shortchanging you a nickel, or telling you that your tshirt sucks).
God help you if you go in looking uncomfortable. Like blood on the water.