Mark, I understand your argument about the infallability of the Church and the fallability of Church members, and i’m sure this makes sense to someone within the church. but what would be the logical conclusion of someone not in the church?
For example i was recently reading The Alexiad by Anna Comnene (12th century) in which she describes the byzantine reaction to the crusades. She was shocked at the fact that not only did the crusaders emblazon the cross on their shields and swords, but also that priests and bishops dressed for war and participated in battle. The battle in question, according to any historian worth his meat, was the conversion of the orthodox east. (the most often cited monographs would be those of S. Runciman or J. Harris).
And of course the mission was eventually accomplished in 1204 with the sack of Constantinople, the forced conversion or exile of all Orthodox priests and bishops and the imposition of a Patriarch loyal to Pope Innocent III who had incited and blessed the crusade beforehand. To the outside eye this would seem like more than a few bad apples; rather it appears to be a top-down, organised, and deliberate effort to force non-catholics to convert. Nor does it seem to be an isolated event if we take into account some of the examples previously given, such as the forced conversions in the Americas. Of course there have been improvements recently, especially as the consensus among RC theologians (if i understand them correctly) is no longer one that condemns to eternal damnation anyone who is not in allegiance with Rome, thus removing the conversion imperative.
Obviously no church can point to its members and say “look none of them has ever sinned,” but to follow your contention i do think we need to look at the fruits of each church with an eye to figure out how some of those sins originate and how they are later justified.