I'm fairly sure that if there are aliens, they do not pilot saucers. Sorry to carry FE theory into the Alt. Science forum, but "space travel" in the traditional sense is a physical impossibility if one subscribes to the theory of Universal Acceleration.
Aliens could well exist on other planets, but their method of interplanetary travel would have to be more of a "boat", in order to travel across the Universal Accelerator (any object flying above the UA would instantly "fall" (the UA would crash into it) but it's feasable that travel on its surface could be possible since the planets are suspended on it).
If flying saucers within our atmosphere really do exist (which is dubious), they're almost certainly just souped-up Conspiracy aircraft - broadcasting satellite signals, transporting the head honchos of the Con from nefarious meeting to nefarious meeting, and guarding the Southern Ice Wall.
My own personal take on the alien thing is this:
A race of beings, capable of faster than light travel (they would have to be in order to come to our world as often as they are shown to do so, in all their myriad forms and functions), would be so far ahead of us technologically, mentally, and perhaps physically, that they would not BOTHER. We would be about as interesting to such a powerful race as say, a moth you see fluttering by as you burn brush after clearing it. They simply wouldn't care.
But, even that stance has holes. The biggest being, I am trying to compute alien mindsets to my own humanoid set of preconceived notions about what humans do. A race from another world, regardless of intent, would be beyond classification by human standards. They would be unfathomable to us, and us to them, and, in all likelihood, would defy all our ideas of what an "alien" really. I mean seriously, they could be sentient grapefruits. Who knows? Maybe carbon based life is all over the place, and our own societies are simply too 1 dimensional to see outside life as anything but "this or that".
The other hole in my theory about their apathy and appearance, travel, etc. Is that If they are so god-almighty advanced, compared to ourselves, would we really even be able, with our technological levels, to even be aware they are observing us? I don't know about you guys, but, if a creature from another planet, with the kind of tech some of those Ufologists (I cannot believe there is a science community based off of speculation!) claim these beings possess, I find it hard to believe they would leave traces of their behavior for us "chimps" to stumble onto, potentially giving them pause, or at the very least, upsetting our natural order with what surely must be a sitcom to a higher lifeform.
I just don't see a creature or their race giving two shits about "these strange little things that argue over who has the most sex on their video boxes, and who has the most cows". Simply mindless.