The colour that tells you everything is the one at the second wash, not the first. A good red top comes out the other end looking the same shade it went in, maybe a touch softer in the hand. A bad one goes slightly orange, or pink at the seams where the dye never quite took, and you notice it under certain lights rather than all at once. I've got one top that's survived about sixty washes and gone a shade deeper if anything, and another that lasted four before it looked like it had been left in the sun for a decade. Same red on the label. Nothing in common on the inside.
Red is fussier about company than most colours let on. It sits badly next to orange, obviously, but also next to anything with a warm beige or camel in it, which surprised me, because I'd assumed beige went with everything. It doesn't go with red, it fights it quietly and the red usually loses. Navy, black, white, a cold grey, all fine. Denim is fine. What you're looking for in the top itself, beyond the colour holding, is a weave with some weight to it, because thin red jersey goes see through at the shoulders and under the arms faster than any other colour I own, and you only find that out when you're already wearing it somewhere you can't do much about it. Check the seams for a close, even stitch, and check the dye hasn't pooled anywhere near a seam or a hem, because that patch will be the first thing to go after a season of wear. Buttons or studs in red tops are often where the finish lets the whole thing down, a cheap plastic one dulls long before the fabric does.
Honestly, red isn't the colour to reach for if you're tired, hungover, or trying to disappear into a room. It asks to be looked at, which is exactly wrong for some days and exactly right for others. It's not an office colour for most workplaces, and it photographs harder than it wears, somehow louder on screen than in life. Where it earns its place is autumn and winter, against the sort of grey skies that make everything else look flat, and it's done good work for me at a lunch I didn't want to go to and needed some armour for.
Tomorrow I'd put mine with dark indigo jeans, white trainers, and nothing else competing for attention.