Angel means messenger.
The old lore says demons can't hide their chicken feet. They can change shape but there's always a massive, obvious tell. Likewise, discerning a true angel is trivial
The angel looks like you. Sounds like you. Uses your own mannerisms. The scene will be you talking to yourself. However, they know things you don't know.
For example, in most cases if you need to worship, you should worship your ancestors. Alchemically, your ancestors are you. That's why they share your interests and would reply to any of your requests. As such, speaking to your ancestors will appear, spiritually, as if you're talking to yourself (but again).