Ohhhhh, I am thinking I am way more "lax" about this than some of you. I have zero feelings on socks whatsoever. I, myself, am barefoot pretty much from April to October, lol. (I loves my pedis, for that reason!!)
If a child comes in socks, then I do insist that they wear them, usually. Mommy or Daddy put them on for a reason, and even though I know it's normal for one year olds to try and strip off whatever they can, it's just a pet peeve of mine. It drove me crazy with my own kids, too! But if they are barefoot when they get here, it's fine with me.
I don't feel like feet are all that dirty, especially on little kids. Unless of course you've been running around in something icky. But if we are outside, then we all have shoes on, and I ask that parents have sensible shoes/sandals for their children. I specifically ask for no tiny flip-flops!! Cute, but not practical at daycare.