Lots of eye witness acounts of anything cant be explained. Witnesses arnt always correct in what they see. Just look at court. Because you think you see something doent mean its actually what yo think it is. Ghosts dont make scence, because why on earth would no one who has passed away come to get the world atention to the subject and put the skeptics to rest. Or talk to reletives to put the record strait. Or stay in a house all the time(why not see the world?)? Why would anyone in their right mind do that sort of stuff? And why would anyone beleive that Anna Nocole had sex with a ghost. All the proof there is is that she said so, and she isnt the most reliable person in the world. If you beleive that, you will beleive anything. Who needs proof? If she said it it must be true!! Right? Right?
On aliens, their behavior would not mae sence either because any aliens with the brains to make spaceships would know our tecnology level means we are not a threat to them. So why stay quiet? Mayby because.... there arnt any!
No records exist of a murderd glost popping into court to clear or accuse someone exist. Anyone in their right mind would want to put their killers in jail.