One thing I've had a lot of success with recently is a slight variation on role-prompting: telling the LLM that someone else wrote something, and I need their help assessing the quality of it.

When the LLM thinks _you_ wrote something, it's nice about it, and deferential. When it thinks someone else wrote it, you're trying to decide how much to pay that person, and you need to know what edits to ask for, it becomes much more cut-throat and direct.