I agree that Bill Clinton was, and is, a brilliant campaigner - in a General Election, when he has an opponent diametrically opposed to his own politics.
The problem is that in the Primaries he is using the same sharp wit, strategies, and sly critiques against someone that his own Party has chosen as one of its prime candidates who has the respect, liking and trust of a large slice of not only Democrats, but also Independents and even some Republicans. You cannot use the same tactics against someone who represents your own values, vision and Party, in the same way as someone who is your political enemy.
It's a pity he has not been able to distinguish the difference and yes, his legacy is thoroughly tarnished - we forget about his Middle East peace initiatives, his eventual decision to take a courageous stand in the Balkans, Northern Ireland etc. and see a "bitter', older political hack "strutting his stuff".