So to really drive home the point of looking at them being bad, I made the Endermen freeze and turn towards you when you look at them. As long as you look straight at them, they stand perfectly still and look straight at you. As soon as you look away, they will run (very fast) towards you.
And they teleport. If they’re too far away to reach you in a short period of time, they will teleport about once per second. They try to make sure they always teleport to somewhere you can see, as I don’t want to confuse the player as to what is happening.