I don't always shop clothes, but when I do some things just grind my gears. Based on a true story.

Arrangement

Maybe it's just me, but I usually don't get how things are arranged. Say, I want to buy some T-shirts, and maybe I'm interested in all T-shirts a shop is offering. Well good luck finding all your options in an arbitrary labyrinth of fabric. It's not like you go through some aisles and that's it, store layouts are pretty random (at least where I live). I think it would make much more sense to designate a part of a store for T-shirts, another for pants/trousers/jeans, another for underwear, and so on. Okay, they probably organize stuff by theme, but then I'd argue if it's the optimal way to go about it for most customers.

Fit

Once you figured out which part(s) of your body to cover, you look for style and print. You look for these qualities because these are the ones you can see almost immediately. For the size and fit you have to check the tag(s). I gotta give props to stores regarding size, because the clothes are usually sorted by size. Fit is a different topic though. I know about regular, slim, skinny, long, and muscle fits. A lot of the times I see something I like and get a little excited, but then I check the tag and realize it's not the type of fit I wear. It's such a disheartening feeling that could be avoided by sorting clothes by fit as well.

Fitting Room

Fitting rooms are my pet peeve. First of all there's never enough of them, you always have to wait your line to get one. Finally you get a room and the first thing you do is to mess around with those damn curtains. The worst ones are heavy, tall, and mounted on tracks that don't reach end-to-end, so you have a pretty hard time properly covering the opening of the room. The curtains should be light, just a little taller than a tall person, and mounted on longer tracks than the opening. An even better setup is when there are actual doors instead of curtains.
Inside the fitting you want to hang the clothes you will try, but the hangers sometimes look like scrap metal incapable of holding three or more items. Alternatively, you could use the seating for that, well only if it's not just some tiny circular stool. A bench-like seating is always better, allowing more space and even the opportunity to try how the clothes feel like while sitting!
Lighting is overdone. It's so much sometimes that you get to see a new face of you in the mirror. Shadows are cast by parts of your body that you don't want them to. It's just an unnatural experience and it's accompanied by the unpleasant warmth coming from the heat of the bulbs.

Checkout

In the end you get weary, but if you are lucky you manage to buy something you like. Congrats! Just hope it won't shrink after the first wash, because then you're back to square one. Let's call this the Circle of Life Shopping.