I often wonder if there are extraterrestrials who are living or working on earth that either look close enough to us that it's hard to notice or are disguised as us? It's an interesting thing that i often think about in my free time, even since i was a kid. There was a guy in my town that lived close to me as a teen who was tall at around 7ft, super skinny and super white with white hair who just looked weird. It was pretty easy to notice him but the way he walked without swinging his arms and despite saying hi to him, he would not even look at us and just carry on walking made me and my friends think he was an alien or just had a problem since his eyes were far enough apart to fly a 737 in between.
But if there was an alien here, how would you notice because surely they wouldn't truly understand our way of life and surely would act, wear clothes and speak differently?
So how would you notice an alien trying to disguise and act as a human? Because if you were an alien that was just dropped off here from across the galaxy then you would obviously make mistakes acting human, even if you looked identical to a human.