“Good fit” and “good cut”
When the garment is on, does it have space for body parts, like breasts, shoulder sizes appropriate to the wearer, etc. And if there is no stretch to the garment, it will never sit properly on the body.
When the cloth parts that make up the garment were cut from a cloth, they should all be cut “vertically” to the cloth, not on strange angles, because the cloth itself will stretch in one way. When clothing manufacturers economize on using as much of their cloth as possible, they cut some pieces vertically, but they have other decent sized leavings of their roll of cloth, and they cut other pieces at odd angles, then sew them all together, the seams of the garment will twist and warp because they’re stretching differently, and it will get worse the more you wash the garment.
“Colors” and “dying”
When fabric is died cheaply, the colors will not remain vibrant with washings. Some fabric will bleed when washed, so they put a “do not wash” label on it.
“Prints” and “appliques”
When manufacturers use poor quality rubber or dye prints for the images on a garment, they might look bright and vibrant at first, but when washed the rubber and dye washes off, and the garment looks old.
NOTE: Jacquards are more expensive than prints because while prints are just printed on top, jacquards are woven into the fabric.
“Fabrics” and “fibers”
Quality is evident in the tighter the weave is, so if you can with your fingers push around the little loops of the weaving of the cloth, it is lower quality, and won’t last long. Also, the heavier the cloth is, in terms of the how “well it falls,” shows quality fabric – tight knits fall heavier. This can even be seen in photos of garments, when they can’t be handled in person.
Fibers have an effect on the way garments breath and how the last. Acetate is something people often avoid because it’s not at all breathable (it’s like plastic), whereas polyester is more breathable but not as much as something natural like cotton generally, although synthetics like acetate and polyester last longer.
Cheap quality cotton is widespread these days, in order to meet the worldwide demand for fast fashion manufacturing. Often, cheap cotton will shrink a lot when washed.
Fabric mixes are often used, and when done right, can provide the nice feeling of organic fibers with the strength of synthetics, for example.
“Sewing,” “stitching, and “threads”
“The hem” – the visible row of thread around sleeve ends, collars, etc, when it is bulky and 3d, is considered “bad” while hems that lie flat are considered good – they have “good thread tension.” On the inside, the same hem looks clean and tidy, and some people prefer when the hem is covered by an extra fabric detail or covered with an organza. Sometimes, hems can also not be attached all the way around, so when you move, they will come undone.
These tips are from fashion designer Justine Leconte.