I know it's generally accepted now that UFO (aliens) believers are crazy. I know in the USA it's a pretty common thing to believe you've been abducted. Maybe people really want to be special, so much so they crave the attention they receive when making such a claim.
However they could be right, and one day all the skeptics will be eating their hats in preparation for when the flying saucer lands, and they come and eat our brains.
Who knows? Well you would think the government did, and they keep telling us that they don't. But you would also think they would have a legitimate explanation for such occurances, and would be able to convince the people what they really are.
If someone could explain the phenomena, and replicate it, then I would be totally convinced that it isn't aliens visiting. Whilst they cannot, I am open to believe it is: a funny cloud, someones funky frisbee, birds carrying a trash can lid, aliens in their space ship, military test craft, a prankster having fun at the gullible peoples expense.. and so on.
You can't discredit something whilst you have nothing to back it up, and vice versa.
I'm not a firm believer of the existence of extraterrestrials who our visiting our world, but I am open to the idea. It is feasible, however unlikely.
If you said to anyone 100 years ago that we would have space stations and regular trips to planets in our system, they would think your are crazy. One day, maybe, something will come visit us, and realise how technologically inferior we are.