The most important factor:
Even the best photographer is uninteresting if he's an *a..hole*. If his personality is right, you can look at his work. I would not want to have a spotter as colleague just because his work is good, he has to be a nice person.
I also like persons who like to try new things... At a large airport, you can always discover new spots and shoot at new angles... This is what photography is all about in my opinion.
Everybody can go to the same good old spot everyday and shoot the same angles... I'm getting bored rather quick when doing this.
So, exploring new angles and spots, this is a feature every top photographer should have