What is the origin of the idiom "put lipstick on a pig" and when to use it?

The idiom "put lipstick on a pig" is believed to have originated in the United States in the early 20th century. The phrase is used to describe a situation where someone is attempting to make something that is unattractive or unpleasant appear more appealing or attractive, often through superficial or cosmetic means. The idiom implies that the effort to improve the appearance of the thing is ultimately futile or ineffective, as the underlying problems or flaws remain unchanged.