"Lily-white" is a term that typically refers to something pure and innocent, but it can also be used as a subtle insult. If you're looking for synonyms to express either of these connotations, there are several options available. For positive connotations, words like pristine, immaculate, and unblemished offer similar meanings. However, if you're looking to insult someone without using the word "lily-white," you might consider synonyms like sanctimonious, self-righteous, or holier-than-thou. Ultimately, the synonym you choose will depend on the specific context and your desired tone.