I came across some rumours that at some point during the filming of TNG, Patrick Stewart apparently said something ill-considered which really got up the noses of Michael Dorn and Levar Burton, and relations between those actors became somewhat strained as a result. When pressed on the matter in an interview, he refused to elaborate.
I can only think that whatever he said must have been inadvertently racist since it happened to annoy specifically his two black co-stars; I say inadvertently
because Mr.Stewart really strikes me as a very fair-minded man outside
of his role, not just in it, and absolutely not the type of person to harbour any such attitudes. Whatever he said must have gone down the wrong pipe; but does anybody know what it was??
My own private theory has always been some remark along the lines that black actors were the best to play Klingons.