The Age Old Battle: Fashion vs. Practicality

So all you shopaholics:

Q: What is the best outfit to wear shopping?

As far as preference goes, I personally suppose it depends on the application of said shopping endeavor. Let me explain. 

Situation 1. 

Forgive me in advance for how snobby as this sounds, BUT if I am going shopping and want good service, generally speaking, I will try to wear something nice. This gives me a rather convenient excuse to try on designer loot (with no intent of buying), without having the sales associates whisper behind my back.

Situation 2.

This situation is a straight sneakers, and denim affair. We're talking a back-to-school type shopping trip; the one you loath, but have to do. It's monotonous, tiring, and almost impossible to get through without a large coffee. Fact of the matter, no one actually enjoys this type of shopping trip, but either way, comfy shoes are a must.

Situation 3.

This pertains to the last post. Having experience sample sales in New York at their finest (or worst, depending on how you look at it), I can conclude that the best feasible option for such shopping would be: leggings, flip flops, and a tank top and a sweater- or a comparable combination. The important thing about dressing for this occasion is easy access- now don't let your minds wander. What I mean is, being able to take your shoes on, and off (...and on, and off) without dealing with the fuss of zippers, or laces. This ensemble is practical in the respect that you can throw a shirt or skirt on without having to deal with the hassle of a change room. 

NB: In sample-sale lingo, "change room" is quite literally defined as a curtained off section, with few mirrors, lots of girls, and piles of clothes. 

So anyways, if you're reading, let me know what you think the best possible shopping outfit might be- just so I can put my sisters argument to rest that practicality is the end all be all.