"Just those few cases would be a lifetime's worth of work."

Yes, they would indeed.

One simply does the best one can with ALL the information at hand, and that's the best one can do. It would be best to approach the subject with as little prior prejudice as possible, in order to remain reasonably objective.

I had prior prejudice before my first sighting of these unusual craft in the sky. My prior prejudice at that time was: I didn't believe there were ANY alien interstellar visitors coming here. I didn't believe it, because I thought I was such a smart guy that I already knew the score! I am now somewhat prejudiced in the opposite direction and I think there very probably ARE alien visitors coming here, having had experiences of my own which radically altered my original opinion. ;-) Not surprising, if you think about it. I am definitely willing to change an opinion in the face of direct experience which challenges that opinion.