What is the origin of the idiom "goody two shoes" and when to use it?

The idiom "goody two shoes" originated from the title character of a children's story titled "The History of Little Goody Two Shoes" by John Newbery, published in 1765. is used to describe someone who is excessively virtuous, moral, or self-righteous, often to the point of being perceived as insincere or annoyingly perfect. It is typically used in a somewhat mocking or derisive manner to criticize someone who appears to be excessively good without any flaws or faults.