Ok first of all what can an alien learn from our asses besides what we just ate!!
And have you seen the movie skyline its about an alien race that completely destroys earth pretty much in an effort to harvest our brains because that is what they need to survive. So i think that we are just a farm for aliens thats one theory of mine another is that the aliens will come in peace but humans as stupid as we are will take that as a threat and attack the aliens causing a war between the two races
Another theory is like the movie the day the earth stood still when an alien that looked human was sent to earth to destroy the world destroying everything on the planet because there was no hope for the human race to change cuz they were killing their planet (but in the end he stops it and saves the human race)
naw, man thet been around here probably longer than us. they been monitoring us and intervening when we got ourselves in too deep . they r prepping us for contact on a large scale. As soon as they know we r not gonna shoot at them. Does anyone REALLY believe that we r the only beings in the universe?? please!!!!