There are different magickal models to explain why magick works, very very short explanations are as follows.
Spirit Model (magick works b/c of sprits), Energy Model ( chi, vril … you affect them and get the results) Psychological Model( magick is in your head model, you manipulate subconscious and hence reality ); and information model ( quantum world and hologram and your acts are like scripts, lines added to the huge eternal software)
All of these models have somehow in line with duality of the universe, like atoms you have + protons - electrons … you need both to have the atoms, so in that manner, Angels can be bad, Demons can be good. Like möe you and all of us, we have people that we hated but they are the loved ones of someone else. Things are binary at the end but this is only for a moment, otherwise, everything is mostly gray. So @DarkestKnight is right in his definition. there is no ultimate good or bad not just in that realm nor in the other realms.
As for the depictions, they are generally and must be in conformity with society’s belief, with our common subconscious and depictions.
In my understanding, these are all false because I believe that spirits exist in the higher dimensions and we may never grasp correctly, as long as we are bound to that 3rd dimension their true forms so whatever you see it’s just our imagination and As @Prophet says no one cares. I may imagine you as a young boy with red hair, you may imagine me as a white boy with tattoos on his arms. Whatever. Does it matter after all… no… it’s all in our head and we just guess.
You may watch the video below to see what I mean about dimension and how it affects to forms An old and good video by Carl Sagan.