I once read an article where Edina Ronay said the mark of a good garment is that you should be able to rip the seams apart with your hands and the fabric should not tear in any way.
These days, you are more likely to rip the fabric before the cotton. That's how bad it has got.
The problem is across the entire cycle of garment production: the spin, particularly, nowadays is horrendous. Fibres are too short, that's why everything bobbles so quickly, so buying merino wool/cotton doesn't necessary work.
My mum has recently died and I've been going through her wardrobe. She had garments from the 80s and 90s, from places like BHS no less, and they are virtually indestructible. The quality is extraordinary.
The same is true for all manner of other products: furniture and soft furnishings, in particular.
When people talk about wanting to pay 90s prices, I'm not sure that fits. One measure that stands throughout time is that you should be able to buy a tailor-made man's suit of clothes for the price of an ounce of gold (so a proper Savile Row suit, pretty much). Now that would be about £1200 at today's price, and that's about right-ish. You can buy a ready-made Dege and Skinner suit for £995.
So really, we should be able to pay £60-£80 for a decent, mass-produced lambswool jumper. But we can't.
It's the same when you look at bespoke footwear. You'd need a budget of about £1000 for a handmade pair of boots with cobbler stitching. So you really should be able to buy something fairly decent for about £100-£150 by purchasing mass produced, but these days, boots at this price range fall apart after a few years (the glue goes, mainly).
My belief is that fast fashion is designed to produce extraordinary profits by selling us a load of old toot disguised as speed trends. There's a reason why Gaona is worth $63 billion.
One thing I have found that works a bit is to buy "artisan/hippy" garments made in India/Kashmir from shops that tend to import directly. So if you have one of those old hippy shop in your area (the ones that sell clothes alongside incense and carved bits of wood), check it out. Also check out fabrics spun in places like Afghanistan; my experience is that they are pretty good and there's the added bonus of supporting traditional industries in Central Asia.
Also, if you have older garments that have faded, but the quality of the fabric is still good, dye them! Dylon machine dyes are brilliant for this, and there's no mess. I've revived all manner of old cotton and linen clothes through dying them back to their original colour -- they look brand new.