Where does this idea come from that sandals are okay as long as you don't wear socks with them?
Sandals are NEVER OKAY. Nobody wants to see your stinking feet. Put some bloody shoes or trainers on or stay in the house. There are no excuses.
I remember the good old days when kids wearing sandals were ridiculed, beaten up, and then ridiculed some more. We have gone far too soft as a nation.