Haven't had any little green people or flying saucer experiences, but have known people who have seen strange spacecraft and had experiences. One is a freemason, one is a neo-pagan witch. I worked with one guy who had no spiritual practice that I know of, and he had contact with them while driving down the road, if I remember correctly. I don't know if he was abducted, but his eye had a tiny black circle in the iris after it happened. He said it wasn't there before it happened.
He would get very agitated whenever the topic was brought up, and would go on and on about it. He was absolutely convinced what had happened was real.
It's probably not good stuff to get into, though it is entirely possible there are other sentient, carnal beings in the universe.
From my own experience, things can look completely real, like a human, but you will know right off the bat that there is something terribly, terribly wrong. It's probably how an animal feels in a trap when the fur trapper comes towering over them.
edit for stray random words (which should be for my entire post really)