My dear, it's quite simple.
Gary Cooper always struck me as an intelligent, sophisticated man, especially after seeing him handle McCarthy so smoothly. Why a man of such abilities would want to go into a woodland (with Ernest Hemingway, no less) and shoot small animals in the name of sport was a mystery to me. I found it quite disappointing that such a bright man would want to do such a neanderthal thing.
Joan Crawford was as tough as an old boot, alcoholic, was riddled with neuroses, and probably did some pretty unsavoury things to get where she was. Whether she was a child beater or not is still a matter of some conjecture. The only testimony we have is a book written after Joan's death by a child who was cut out of Joan's will and supported by the other child who was - you guessed it- cut out of Joan's will. The other two girls said the book was rubbish. Who is right, we may never know. I doubt she was very pleasant to live with.
The difference? It comes down to expectation.
Joan is Joan - I anticipate with everything I read about her she will be shown to be a controlling, vodka-swilling haridan, and she never disappoints. In fact she often exceeds that expectation.
But Gary Cooper, who I anticipated would be a little more evolved than the average schmoe, let me down.
Simple as that.