As a backspot, it really depends on the quality of the sock. If they're rougher or cheaper fabric, I can usually get a pretty good grip. If they're smoother or fuzzy, no good. I've asked a flyer take her socks off at practice because they were fuzzy and I just couldn't get a grip. But most socks are usually okay. And it helps if you have sweaty hands? Or if flyers put lotion on. So, doesn't matter much to me, since I can usually get a grip.
Aesthetically, I like them with clean collegiate/high school uniforms. And they have to be white! No black socks. If they wore black shoes, then I would like black socks (ie, Top Gun). But white shoes get white socks!