The Goetic spirits, for the most part, have appeared as very beautiful females of diverse cultures. I have yet to meet Andromalius though. Satan/Lucifer was a guy in a suit. Belial appeared to me, looking similar to Jared Leto below. “A slick lawyer with slick-black hair in a suit.” King Paimon looks like a clean-shaven version of the Dos Equis Beer guy.
The spirits use your representation or understanding of reality to appear and interact with you.
And Duchess Bune has appeared to me like the woman in the photo below. When I first saw this photo, I was shocked. This is exactly how I saw her! Very beautiful, Egyptian (Middle-Eastern) looking but has dimples cheeks, long black hair, slender body, sometimes nude, always barefoot… She’s always smiling and exudes happy energy. and like @AradiaX stated, she can also be “bratty” on occasion.
This is what Queen Beleth looks like when she appears to me. She has very tomboyish mannerisms and has the wisdom of an elder but the delivery of a teenage girl.
When she first started visiting she would switch quickly to a little girl with long pale blonde hair and big black pools of nothing for eyes. Her mouth would be full of razor teeth and she would suddenly be at my face trying to scare me. She hasn’t done that since I made it clear I was unafraid. I can’t find a really good picture but something like this: