I mean you could have the aliens walk out on stage at a hearing and people would still question it... the issue is that when a source such as the military shows un identified crafts they record and says here's a ball flying over Iraq and we aren't sure what it is... it's really the only evidence they can present to the fact that there was something there. The only real way for people to be convinced is through their own personal sightings.
Here are my reservations with that.
In the example of aliens walking out on stage. Am I up close, looking it in the face, shaking its hand, and talking to it? Can I tell if it's a latex suit? Or am I 50 rows back in a sea of humanity where I can't tell anything? Or, am I seeing a video of it? Or am I hearing about it from some random person who was there who can't tell if it's a hoax? Or a person who says he was there, and I don't even know if that is true?
In the example of the ball over Iraq, is it really from the military? A couple of UFOlogists say it is. Regardless, the video I can see isn't that compelling to me for technical reasons.
However --
If we could get the level of evidence like we see in "JFK and the Unspeakable", by Douglass (a book you'd love, DmonSlyr -- I highly recommend it and think it's awesome), or in "Blindman's Bluff", by Sontag, Drew, and Drew -- that would drastically change my skepticism. Seems to me there ought to be at least that much solid evidence out there to gather as for those topics.