I nearly didn't try sock boots on at all, on the grounds that anything with a name like that sounds like it was invented to be fashionable for one winter and forgotten by the next. I was wrong, or at least only half right. A good pair earns a place in the rotation for years. A bad pair stretches at the ankle by November and looks like a flattened welly by January.
They do more ordinary work than you'd expect from something that looks quite dressed up on the rail. Under a straight skirt and a plain jumper they read as neat rather than try hard. With jeans tucked in, or just jeans left loose over the top with the boot peeking out at the ankle, they do the job trainers usually do but with a bit more polish for an evening that needs it. I wear mine with a longline cardigan and not much else and it passes for an outfit I thought about, which is more than most outfits get. The one thing to watch is proportion. If your trousers are wide at the hem, a sock boot with a pointed toe can look like it's trying to escape, so either go narrower above or accept the look is a bit more fashion forward than you intended.
Fit is the whole business with these, because there's no separate zip panel or buckle to rescue a bad call, the fabric simply has to sit right against your leg. Go by your usual shoe size first, then pay attention to your calf rather than your ankle, since a boot that's generous enough for a wide calf will often gape at a narrow one, and a boot cut for a slim leg will dig in uncomfortably above a wider one by the second hour. Try sitting down in them in the shop, not just standing, because that's when the fabric either moves with you or bunches at the ankle crease in a way no amount of fashion forgives. Check the sole flexes where your foot naturally bends, and look at the inside seam where the knit meets the shoe part, since that's the first place a cheap one splits.
The difference between a good one and a disappointing one is almost always in that join. A well made sock boot has the knit fused or stitched properly to the shoe, not glued on in a way you can peel at with a thumbnail, and the knit itself has some structure rather than going baggy after one wear. Reach for them on the days you want a boot that looks finished without any fuss, and be glad, as I was, to be proven wrong about something that sounded like a fad.