I find words totally unnecessary but can't refrain!
There is NEVER a time EVER that socks should be worn with thong sandals. Not even in the privacy of your own home. I even question wearing socks with non-thong sandals. The only exception I can think of is this - maybe in the dead of winter, in the middle of the night because you have to walk your dog. BUT NOT on a hot humid 100 degree Sunday afternoon in public - even if it is the local gas station.