Yeah, I can see you runners out there wincing and feeling your blisters. The fact remains that for light exertion, I haven't found anything more comfortable than cotton socks. Not wool (*really* not wool), not exotic two-layer technical confections (great for actual running, but not for everyday use), and certainly not soft polyester. But there are a lot of "cotton" socks out there made of something like 70% cotton, 20% polyester, and 10% something stretchy. I've never been happy with these -- they don't absorb sweat properly; they don't dry gracefully, and the cotton leaves them before the other ingredients, so over the life of the sock the polyester content keeps going up. Finally, you have a very sheer polyester sock with a few cotton bits stuck in it. Not good. You do need a bit of something stretchy in them, but in general, I can gauge my reaction to a sock by reading the fiber content.
Over the years, I've found a number of good cotton socks, and lost them again -- they keep going out of production. JCPenney for years made cotton work socks that were inexpensive, reasonably durable, and came in an amusing kraft-paper package with stencil-style lettering on them. Butch socks. They stopped selling these around 1986. More recently, the Gold Toe people had acceptable socks, but sold them under the same name as a high-polyester "cotton" thing, and packaged all of the above in plastic. I like the (now really worn-out) socks that I have, but I can't find more.
If there's anybody else out there who likes cotton socks with lots of cotton in them: Wigwam brand #F1055 "King Cotton" socks are the real thing: 95% cotton. And they come in sizes that fit feet from size (EU sizing) 37 to 51. My size is 'large', though 'medium' would probably work fine too.
And -- I'll be able to find this post the next time I need socks...
If you've stuck it out this long on footgear, I might as well switch gears and talk about where search engines fail. There are lots of common tasks, many of them related to housewares. Want a towel? Easy. A cotton towel? Simple. An all-cotton towel? Harder, but still pretty easy. A towel that's at least 50 inches by 32 inches, but could be larger in either dimension? Nope. Search engines don't tokenize numbers as numbers well or often, and don't do comparisons.
Similarly, a search string for socks of at least, say, 94% cotton content looks like (94% OR 95% OR 96% OR 97% OR 98% OR 99% OR 100%) AND "cotton socks". What you want is a search for cotton socks that's ranked by cotton content. Possibly with "unknown" as an option. What you get is... less useful.
And all this is much deeper below the CompSci radar than, say, image recognition and categorization.
W3C standards for product descriptions, anybody?