Aliens are another one of those things that I think of as sexless... though I feel like E.T. was probably a guy. Then again that really long limbed thing that came out last in Close Encounters I feel like was maybe a girl. Both generally sexless though...
Anyway, aliens are dumb. Especially if they have issues with water, a la Signs. Oops, guess that's a spoiler, but it's so old I figure that it doesn't matter at this point.
I prefer to think that if we got aliens though, the water hating kind might be good, otherwise we are pretty much doomed.