I hope I can speak with some authority on this issue, as I live in a hemp wearing, granola eating, last (and unfortunately, no longer lost) hippie backwater rapidly becoming inundated with lifestyle challenged commuters and recent retirees who want to 'get away from it all', but have actually 'brought it all with them'.
Fact: Socks become wet when worn with sandals and it rains.
The issue is not the fact that people wear socks and sandals, it's if they express surprise when their feet get cold and damp during the rainy season. Gum boots were invented for a reason.
Now, secondly, it is not the 'socks with sandals' thing that really sets one apart as being clothing challenged. It's SHORTS with socks and sandals. BAD FORM.