I live in Australia, and while we haven't had many "good" Prime Ministers, none have been incredibly bad.
When I say bad, I'm talking about Buchanan bad, I'm talking about Syngman Rhee bad, I'm talking about Idi Amin bad. When you see how bad other leaders can be, it makes you thankful that at the worst, our leaders can be slightly mean and incompetent. We've never had a genuinely evil person in power. Yes, I didn't like Howard, but the man wasn't evil, not by any stretch of the imagination.
The absolute worst leader we've ever had would have to be.... hm. Well, John Howard. No, I don't think he was totally evil, and he did some good things and generally managed the economy pretty well as well as Law and Order issues. However, he got us involved in Iraq due to his brownnosing of the American President. He also delayed action on Climate Change, and he once tried (this was before he was Prime Minister) block refugees fleeing communist prosecution from Vietnam from entering Australia. He was a mean old bastard, and I never liked him because I always suspected he was racist against Asians. Given that I'm half Chinese, I always suspected he was half-racist against me.