You can usually tell a good streetwear piece before it's even on, just by the weight of it in your hands. A hoodie with proper substance to the fleece, a bomber with a lining that doesn't feel like a crisp packet, cargos with hardware that actually clicks rather than rattles loose. Cheap versions feel thin and eager to please. The better ones feel like they already know what they're doing.
This is clothing that's meant to be lived in, so the real test is what it looks like after a few months, not on day one. A good sweatshirt softens and moulds to you without losing its shape across the shoulders. Decent cargos keep their colour instead of fading to a sad grey after three washes. Cheap oversized tees tend to go long and thin at the hem first, which is how you know they were never going to make it to winter. The washing matters more than people admit. Turn things inside out, go cooler than you think you need to, and resist the tumble dryer on anything with a print, because that's the fastest way to turn a graphic into a cracked, peeling mess within a month.
Fit does a lot of the talking here. Oversized only works when it's oversized on purpose, through the shoulders and body, not just baggy everywhere, or you end up swamped rather than dressed. Cargos should sit low enough to look right but not so low you're hoisting them up every time you walk anywhere. Cropped layers over longer ones is the whole trick, and getting the proportions wrong is the difference between looking put together and looking like you got dressed in the dark.
Where it falls apart is in the mixing. Too many logos at once and you look like a walking advert rather than someone with an opinion. Pairing chunky trainers with anything too delicate up top undoes the whole thing, it just reads as confused rather than considered. And layering for the sake of it, three hoodies deep because you saw it done somewhere, mostly just reads as hot and uncomfortable, which, speaking from experience, it absolutely is.
It's also not built for every room you'll walk into. Anywhere that wants you softer, smarter or quieter, this will fight against you rather than for you, and no amount of styling fixes that mismatch. It's not a disguise for not knowing what else to wear either, it rewards people who've actually thought about proportion and colour, not just thrown on the baggiest thing in the pile.
Worn with intention, though, it holds up far longer than its reputation suggests, and ages into something that actually fits you better than it did new.