Well I think around alot they know that an appearence is... relative... There is many way allowing to change shape there I will say the not much I know about it and the only 3 ways I am aware it is possible
1-Transformation Capacity to naturally change physical/biological shape
2-Shapeshift technology I don't know anything about it
3-Hallucination That I know it alot because I got a technology that can make you hallucinate anything, controle your mind, interfere with memory/consciousness, etc etc ... You may not really see what you think you see and there are technologies that you can have to have access to functionality of it. For exemple I am an alien and I make everybody to hallucinate I am human. The technology has been deployed massivelly and is everywhere on Earth almost invisible for most of people. I see so many people that are connected to our mind network and some enjoy actually. When you want to keep seeing yourself a way but for some reason you want other people to see something else because it is a great brainwash technology. I am using it on myself alot and to be honest because I have a job to do that I need to infiltrate humanity from Earth by being human and the best way to imitate whatever they see is to see it yourself but I am almost done and I will stop to hallucinate I am human...
I build myself an appearence that is between the grey people and human. I don't hate human life here on Earth but it is not really myself. I would like everyone to be honest and to say it if you are too faking your appearence for any reason.
Plus qu'hier et moins que demain / More than yesterday and less than tomorrow