This is an entertaining thread from Catholic Answers:
Infallibility of canonizations
Here's some choice snippets showing the "clarity" of the infallible church of Rome:
"What does one say to a Catholic who refuses to believe canonizations are infallible despite having heard quotes from Ludwig Ott, St. Alphonsus Liguori, and similar sources? He's like, "Church teachings are only infallible if they've been taught from the beginning. Even the Catholic Encyclopedia only says that most theologians believe canonizations are infallible, not that the Church explicitly teaches it" (at least that's his argument in a nutshell). Just for the record, this guy claims the Church was wrong to beatify Bl. John Paul II (I won't go into why he believes that) and says that should His Holiness be canonized, he will continue to be "charitable" and pray FOR His Holiness."
"Well, the guy is correct that the Church has never formally and dogmatically defined the infallible nature of "modern" canonizations (ie, canonizations performed using the process we have today).Theologians believe this teaching is part of the Sacred Tradition of the Church (which is infallible, but is not as easy to quantify)."
[On JP 2] "If he wants to pray, let him. We tend to think of saints as the one' who have 'made it', like they have graduated or something. That is not necessarily so, it could be that there are degrees of holiness, and that people could improve even in the next life. Perhaps he could use the prayers after all."
"Well, you're correct that there will be degrees in heaven, corresponding to the degree of holiness we attained while on earth. But in heaven, whatever degree of holiness you attained while on earth is fixed. Besides, those in heaven don't need prayers; those in purgatory do."
"That's nonsense. What Church teaching/document supports such a claim?"
"The following passage can be found here: http://www.newadvent.org/cathen/07170a.htm.There are various degrees of beatitude in heaven corresponding to the various degrees of merit. This is a dogma of faith, defined by the Council of Florence (Denz., n. 693 — old, n. 588). The Bible teaches this truth in very many passages (e.g., wherever it speaks of eternal happiness as a reward), and the Fathers defend it against the heretical attacks of Jovinian. It is true that, according to Matthew 20:1-16, each labourer receives a penny; but by this comparison Christ merely teaches that, although the Gospel was preached to the Jews first, yet in the Kingdom of Heaven there is no distinction between Jew and Gentile, and that no one will receive a greater reward merely because of being a son of Judah. The various degrees of beatitude are not limited to the accidental blessings, but they are found first and foremost in the beatific vision itself. For, as we have already pointed out, the vision, too, admits of degrees. These essential degrees of beatitude are, as Francisco Suárez rightly observes ("De beat.", d. xi, s. 3, n. 5), that threefold fruit Christ distinguishes when He says that the word of God bears fruit in some thirty, in some sixty, in some a hundredfold (Matthew 13:23). And it is by a mere accommodation of the text that St. Thomas (Supp:96, aa. 2 So you see? Nothing nonsensical about that. Care for some salt or pepper with that crow?"
"As you are directing me to The Council of Florence document as your support can you please at least direct me to the section/paragraph in the document so I can read what it says or have you not actually read it and are simply looking to an encyclopedia (not a Church document) article to support your claim."
"Indeed. The "canonization process" of the ancient Church was not formally defined, but rather was an act of public acclaim (Mary, the Apostles and other notable biblical figures, as well as the Christians martyred by Imperial Rome, where proclaimed to be saints by Christians). I think this could be considered an aspect of sensus fidei and therefore, as you said, it would have certain infallible guarantees associated with it."
"Jesus said, "In my Father's house are many mansions. If it were not so, I would not have told you." (John 14:2) Some interpret this passage to mean, "there's plenty of room in heaven." But Catholic theologians traditionally interpret it to mean that the experience of heaven will not be universally consistent for everyone. I would not characterize this as "levels" or "degrees" but different experiences."