Thanks guys, I understand now, from what you've described you're shadow people are more like silhouettes than shadows. I can see why the dark featurless figures would freak people, you wouldn't be able to judge their posture or the look on there faces, making them automatically less 'human' and more the dark malevolent 'thing'
The shadow people I've always seen are shadows, but solid, they have form and shading within the darkness and although by the time my brain has told me there's somebody there all I can see is the shadowed form I've always been able to describe what they looked like, it's almost as if the logical bit of my brain kicking in and telling me that what I'm seeing couldn't logically be there so it doesn't have to fill in the details.
The shadow people I've always seen are shadows, but solid, they have form and shading within the darkness and although by the time my brain has told me there's somebody there all I can see is the shadowed form I've always been able to describe what they looked like, it's almost as if the logical bit of my brain kicking in and telling me that what I'm seeing couldn't logically be there so it doesn't have to fill in the details.