I met Nichelle Nichols in 1990 at a reception in honor of the 15th anniversary of the Apollo/Soyuz mission. There were a bunch of astronauts there, and Nichelle. They were all polite, but you could feel the arrogance. Nichelle was like an old friend. She chatted a long time. Then a couple of years later I saw her at a convention. She was very distant, and "guarded" by her enterauge. Not out and out rude, but distant.
I've never really had a totally bad experience with any.
I will put my $0.02 in. Cut Walter Keonig some slack. He's had a terrible year. He's back at conventions, but everything must be hard for him these days.