Man, I think having aliens visit us would be cool, but I have some general worries about them. One is if an alien were to crash on earth, depending on where they land, they would have vastly different ideas of what the human race is like. Crashing outside CERN or NASA would be best case scenario, worst might be the boonies in Kentucky or the middle east. To think we could either be showered in alien knowledge or having our planet clensed with plasmic napalm, based entirely on who the aliens visit first. The second is considering all of the radio waves and transmissions we send out, I've always wondered if aliens were scanning our solar system for life, and the first transmission they received was some Internet video of a guy shoving golf balls in his butt, and all of their preconceptions about us were built around that one video. Then they start abducting us and stuffing our butts with food to feed us, but we keep dying and they dump our bodies back into the woods, then we find all these corpses and think some insane murderer is running around doing all these terrible things. I bet if we capture an alien, we'll probably try and stuff food into it's gills to feed it, so it goes both ways I suppose.
Sorry, brain dump