Hmm... in my experience, mine came to me. And I knew about her before I knew she had a term, or that other people had this experience too.

So knowing that, I would say... I don't think your dream guide should want to hide from you, or to keep his identity a secret.

I guess you'll just KNOW when you find your DG. Because it's true, they aren't like normal DC's. They have an intelligence and there certainly is a strong bond. But when mine is around... I don't know. I would just never question her honesty. Because it's all there, out in the open. She is my guide. She is there for me, to help me. To teach me things. It's just a feeling I get, a profound knowing.