What is the origin of the idiom "like death warmed over" and when to use it?

The idiom "like death warmed over" originated as a vivid and exaggerated way to describe someone who appears extremely sick, pale, or unwell. It is a figurative expression that suggests a person's appearance is reminiscent of someone who has recently returned from the state of death. It is used to emphasize a person's extremely unwell or unhealthy appearance. It suggests that the person looks very pale, thin, or exhausted, as if they have been through a tough time.