What does "spit and polish" mean?

Close attention to appearance and order, as in With a little spit and polish this house will sell very quickly. This expression originated in the military, presumably alluding to literally shining up something with the aid of a little saliva. There it also came to mean “too much attention to appearance, and not enough to more important concerns,” as in The commander is so concerned with spit and polish that he overlooks the crew's morale. [Late 1800s]