Aretha has been a bit notorious with her "beefs" with other artists. She and Anita also did not get along for years but Chaka and Aretha are surprisingly very close. I always wondered what was the tiff between Gladys and Aretha. Gladys just said that Aretha had a problem giving respect and left it at that. I honestly believe that Aretha has a fear of being upstaged. A friend who was a member of the choir for the gospel segment of the 2008 Grammys told me that Aretha snapped at BeBe Winans during the rehearsals stating that he was singing on her lines. All hail the queen. Now I have NEVER, EVER heard any negativity about Gladys Knight's character. I've seen her in concert a few times and she has always been very personable and come off as very down to earth.
BobC, I don't see Gladys publicly stating her frustration with a part of the industry that she's frustrated with as an example of her character as a person. That's an entirely different can of worms that I'm sure other artists could relate to whether they care to state it publicly or not.