This is a topic which has always fascinated me : the way spirits we are working with decide to show up in your dreams. It is an interesting way to find commonalities or to see if they decide to appear in a total different way depending on the Magician.
For instance, I had faeries showing up as skinny brunettes with clear blue eyes showing up and acting flirty.
Tree spirits tend to appear as old wise men usually dressed in white or with white hair.
The Archangels are always represented as soldiers, policemen or secret agents. This is how I know I'm dealing with them. Makes sense to me because I attribute to them the quality of order and justice.
Moreover it is not rare when dealing with the Archangels thatI find myself in some kind of University/School where I am there to pass an exam (which usually scares the s*** out of me).
I would be curious to read how the spirits you are working with appear to you and if likewise you have some "codes" making you be aware of their nature.
Thanks!