I guess I'll put my two cents in since I've been both a customer and a retail employee. I've worked in Hechts (Like Kaufmanns/Strawbridges etc.), Filenes Basement and Nordstrom. Each store has a different compensation structure which will often determine the level of service you receive.
At Filenes Basement, you get $6.25/hr. with no commission and a 30% discount. Not bad, but the people who work there aren't about to help you coordinate outfits, they're too busy putting stuff back from the dressing rooms and straightening racks. Management doesn't keep enough employees in the store to do anything but keep it open and the cash registers ringing. Its a friendly working environment and relatively stress free. No one receives commission, everyone starts out part-time and you don't get any benefits until you're full time.
At Hechts, they started me at $6.75, also with a 30% discount. Managment didn't give a crap about anything other than pushing merch out to the floor and ringing the registers. Employees are treated like meat and treat the customers accordingly. Coupons are the bane of any workers existence (i.e. the SAME SALE runs EVERY WEEKEND but people think because its a "coupon" you get more than you got LAST weekend). NO respect and it shows in who helps you. The only people in the store who got commission were shoes and furniture. Everyone else is working poor.
At Nordstrom you get the best of the best. I think I got $8/base back in 1999 with a 4% commission on whatever I sold, which at the time was ladies accessories and later ladies bridge apparel. Commission depends on whatever department you worked in, and everyone received it. Here salespeople will escort you around the store to make sure you find a sweater to match your favorite brooch and personally take your pants to the in-store tailor if you need a rush. Sales floors are not crowded so that people may safely navigate the store and that people with disabilities don't feel crowded. A pleasant working environment, but the staff can get very competitive with commissions. Seniority is usually an excuse for taking someone elses sale. Employees often have college degrees and are highly motivated. The discount was 20% for regular employees and the best seller in each department received a 33% discount for the following year. You can actually make a living wage at this job, the only one of the three stores its possible at.
When you're working on commission to feed yourself you start to become a bit pickier about whom you spend a lot of time with. Imagine how it is to "invest" an extended period of time with someone who needs a lot of assistance but doesn't ultimately purchase anything. There is an opportunity cost - the cost of what someone else could have added to your paycheck instead. You choose the guy in the Ferragamo loafers over the Birkenstocks. I'm sorry, but its true. In your position you'd do the same. Maybe not at first, but once you see its impact on your paycheck you feel the consequences of your decisions.
While each of these retail stores are not "luxury" hopefully it will give everyone some insight into the person across the counter. I'm finishing my masters in April and work retail to score some easy cash and a good discount. Another of my colleagues is midway through her PhD. Snottiness is never acceptable but sometimes you're only as good as the people standing behind you in managment. Associates don't make up lame return policies or have any say in much of what goes on in running a store. Hopefully what I wrote above will shed some light on to why associates behave the way they do in each of those types of store.