The Spartans were also very particular about their hair. They sometimes insisted that battles be postponed so they could ‘do the doo’ just so.
They were a bunch of pederasts, figures they were fussy about their hair. :^)
They made themselves more beautiful, more terrible (there's a three part Greek phrase, but as the saying goes, it's all Greek to me) before they engaged the Persian host on the final day of Thermopylae -- the Persians spies reported that they appeared to be preparing for a party, and everyone had a good laugh, that is, other than the piles of Persians who had already been slain.
The battle was a face-saving move by Sparta, which had a well-deserved reputation for unenlightened self-interest and taking payoffs from the Persians. It had no impact on the outcome of the Persian invasion, merely delayed the host a few days. Themistocles' plan was followed and led to the near-annihilation of the Persian fleet (some of which was made up of Greeks from Anatolia who lived under Persian rule).
BTW, the three part phrase is described by Bettany Hughes in "The Spartans" (check YouTube).