when ski boots are fitted, they are done so to the shape of the foot.
If you have a huge sock on & then get the boot fitted, your foot will wobble about even when it feels tight. As a result you get less response & control of the ski, more so that might be thought.
Thinner socks give you the correct amount of room between foot and boot to keep control, and keep warm. Air is the best insulator, so a small layer of it rather than a thick sock is actually warmer. Thats why double glazing has a small space between the panes.
Better socks are therefore thin, and these are a bit to thick for me. Better boots tend to be tighter, so these arent quite what i was looking for.
BUT for the price, not bad as a back up!