Spartans and most ancients (Celts being an exception to the rule) did not fight naked. The image of Greeks fighting naked is probably somewhat based on the ancient Olympics, where they did compete naked, and the sculptures and statues from that period. They may have been barefoot, it seems thats one issue thats sometimes overlooked, though sandals may well have been worn. Considering the terrain, I would think so. One of the ADVANTAGES the Spartans and other Greeks had over their Persian enemy was their heavy bronze and leather armor, including helmet, body armor (cuirass), leg armor, shield, and skirt made of leather strips. Naked Greeks would have been at a disadvantage when facing Persians with even their light armor.