What makes a "cycling sock" a cycling sock?

[mustang1]

It must be given away free with a cycling magazine.

Or a bike mag does a review on socks highlighting the merits of a cycling specific sock.

 

[JtB]

Black, have left and right on them

Until recently I though so too, but my latest Bianchi cycling socks although black do not have L and R on them so I no longer know which feet to put them on.

 

[ianrauk]

Socks