Flaws which can be cured easily:
- absent buttons (you can do it yourself!);
- broken zippers, snap fasteners too loose or too hard/impossible to snap (there are usually extras and you can change one or two of them, it’s quite cheap);
- too long hem and sleeves if garment lines are simple and there is no problems with pattern, no lining, alteration isn’t big;
- two big waist if alteration is not bigger then two inches and there is nothing to complicate things;
- lining is too long.
Flaws which can be cured, but require a really good seamstress/tailor:
- too long hem and sleeves if garment lines are not that simple, garment has lining, too long sleeves have cuffs etc
- too big waist if it’s more that an two inches to be taken in (beware of pockets! and button holes! sometimes they are reason why waist can’t be taken in more then couple of inches)
- horizontal folds under buttocks (trousers and jeans); it occurs if buttocks more flat then garment was made for;
- too broad shoulders;
- small horizontal folds where sleeves are attached.
Flaws that normally can’t be cured:
- it’s too small (beware that shirt or jacket can be too small in the front and too large in the back, so when you fix the back you won’t be able to button it, or you will be getting ugly folds and flattened breasts);
- button holes are not in a line;
- major asymmetry of garment or lining, lining is too small for the garment;
- it’s way too big (well, it can be cured, but it costs as much as make it from scratch or even more);
- details have different colour (can occur on velvet because details have different direction of pile e. g.);
- you put your hand up and garment moves up, movements are strained;
- small horizontal folds under the crotch.
One of the problems of busty women is that most tops from high street have such flaws as “too small (in the bust)” and “way too big everywhere except bust”. It’s not that bad if you have broad shoulders and long arms (because waist can be taken in quite easily and you can elongate back darts to make back more narrow). But if you have narrow shoulders and shorter arms, then sizing up 3-5 sizes and then taking in isn’t going to work for most of garments. Exception: garment has no seams on shoulders (kimono sleeves, bat sleeves, raglan) and there are no cuffs.
Small pleats (large pleats usually don’t look good on us and elastane/jersey are also good things because you can get away with significantly smaller alterations then.
So I think that for woven fabrics (if there are no additional factors mentioned above) it’s better to stick to speciality shops and for jersey and garments without shoulder seams and cuffs it depends on how expensive are alterations where you live. If it’s cheap or you are any good with sewing machine then you have a nice option of buying from high street and altering.