Nobody’s perfect. That includes ministers of the local ecclesial communities and Catholic parishes. Some folks would have us believe that it is intolerable for any cleric ever to sin, and that those ministers who habitually do wrong prove that Christianity (or at least “institutional religions”) are false or fraudulent.
This criticism would only be valid if the Catholic Church (or the Orthodox, or the various Protestant communities) ever claimed that a sign of their doctrinal purity is the moral purity of every one of their ministers. But they don’t claim this, and the claim that ministerial wrongdoing somehow just ipso facto disproves anything is not true.
The Catechism says this:
All members of the Church, including her ministers, must acknowledge that they are sinners. (CCC 827)
The mistake these critics make is likewise demonstrated by the fact that the Lord Jesus chose Judas Iscariot (the man who betrayed Him, and a man who was a petty thief) as one of His twelve apostles! The point ought to be obvious: there have been and always will be sinners in the ministry because all men are sinners. There is no one among us who is sinless, so there cannot be a single priest or minister who does no wrong—and some will be worse than others, as the pedophilia scandals amply testify.
Yes, men in positions of authority do evil things. Yes, men who ought to be examples of good behavior are among those who do evil things. But if Judas Iscariot was an apostle, then the truth taught by the Church is in no way invalidated by her clerics’ misdeeds.