Livius, in my own life I find it hard to make this distinction. How can a leftie be good? Seriously. Think of the opinions they hold, think of how their minds work, think of who they vote for. They are who they are and think the thoughts they do for a reason, and it's not because they're good. In fact, they often loathe what is good and spend a lifetime opposing it.
He's actually been very anti-abortion, pro-marriage and family, and fairly orthodox in many other things (clamped down on the wimmin-priest stuff that was going on here, for example).
But his political opinions, particularly relating to Bush, the war, etc. are extremely left-wing. He was in Latin America for a number of years and obviously drank deep of the liberation theology (aka, anti-US) garbage. I think he has realized that he has got to separate that from his diocesan work, though. For one thing, Jacksonville (part of the diocese of St. Augustine) has many military families and someone finally managed to get through to him that he was being extremely cruel to them in his comments.
I think it's worth writing to them because you never know. Leftists live in their own parallel universe, and sometimes they simply aren't aware of the reality of other people's lives. (Particularly, I suspect, among the clergy, who are in many cases totally self-obsessed and unaware that anybody else in their parish even exists, to say nothing of being of any value.)