I suppose it would be best to convict someone based on the fact that he is a cad?
He never told her anything that would implicate him in the murder of his wife. Only that he was cad/dog and wanted the best of 2 worlds. Her testimony In my opinion did not seal his fate, if you have circumstantial evidence it helps to add the cad factor and he was convicted, no more no less imho.
It is an interesting ploy to make the jury hate a defendant and the prosecution through Amber showed him to be a casanova and turned up the hate factor.
Perhaps that's so. But I do believe it also bolstered the prosecution's theory as to motive.