The way Earth fights amongst it's own countries do you think it would be any different between worlds?
And if we are visited in our life time it would mean whoever they are will be far more superior in technology and science than us and most likely would be unstopable in an "Independance day" senerio.
And if they truely come in peace they must already know about our capacity for violence/war and wouldn't want anything to do with us.
And what if we were to have the means to travel to the next M class planet <--(ya like that?
) and the inhabitants were more primative than ourselves would we let them be or put a flag up?
So...I'm not to sure I would like aliens visiting our planet, especially on a school night.