The best thing to do in order not to be seen is just not to exist.

The point im making the mad axe man could not see me so i did not exist. So your room was never invaded by alien creatures as a child, how fortunate for you.

Where does our other sensory inputs go into this? If i have a blind fold on and i feel something, does that make it exist? All seeing is, is the refraction of light and the output of our brain when it is processed. I can not feel gravity, but it does exist because it effects me. The question is not whether something exists, but if if i am aware it exists.