The major effect of the ambiguity of the Vatican II documents is the emergence of two divergent methodologies used in interpretations of Church statements, one favoring a innovative approach and the other an approach in keeping with Catholic tradition. These two methodologies have been dubbed the "hermeneutic of rupture" and the "hermeneutic of continuity", respectively.
Now, if the documents of the Second Vatican Council were not so intentionally ambiguous in some of their most important doctrinal and disciplinary statements (what Michael Davies calls "time bombs"), we would not even have two opposing "hermeneutics" to worry about. Nobody who reads the Syllabus of Errors or Lamentabile Sane can possibly argue about how to interpret them. But not so with Vatican II documents, and with every Church document promulgated since then.
All of us, Traditionalists, conservatives and liberals, have grown accustomed to having to look beyond the plain language of a document in order to draw out the true meaning, often because the plain language is so elusive. One effect of this unfortunate trend is seen in what I have called "the hermeneutic of exceptions." This is the principle that whenever the Church lays down a norm that is universally binding but, through concession, permits some small exception or deviation from the norm, that minor deviation is latched onto, the regulations governing it are so extended and watered down, and soon the exception becomes the norm, the norm becomes a dead letter, and is soon relegated to the realm of discarded Traditions.
Take, for example, the famous case of Sacrosanctum Concilium 36, which states that "(1) Particular law remaining in force, the use of the Latin language is to be preserved in the Latin rites. (2) But since the use of the mother tongue, whether in the Mass, the administration of the sacraments, or other parts of the liturgy, frequently may be of great advantage to the people, the limits of its employment may be extended." So here we have a directive ordering continued use of Latin, but a secondary provision allowing use of vernacular when deemed appropriate by competent ecclesiastical authority.
But what has happened? Has Latin been preserved? Certainly not! The exception to the rule, that vernacular could sometimes be permitted in certain situations, has become the norm in the entire Latin rite, so much so that liberals now speak nervously about the possibility that the Church might someday "return to the use of Latin." This demonstrates that they have so changed the exceptional use of vernacular into the norm that they honestly think Latin has been abrogated or is not still the official language of the Church!
Another instance of this hermeneutic of exceptions is in the interpretation of the Church's doctrine on the possibility of persons in a state of invincible ignorance being able to attain salvation. Have you noticed how widely this was applied? Conservative Catholic apologist James Loukidis, for example, has applied the doctrine of invincible ignorance to the pagans gathered at the Assisi Prayer Gatherings in 1986 and 2002. How can pagans gathering in Italy at the invitation of the Pope himself be considered invincibly ignorant? Too often this teaching of the Church (which only says that the salvation of invincibly ignorant persons is possible) is extended in such a way to imply that all non-Catholics are saved. In actuality, there is almost nobody alive on the earth today who meets the criteria for being invincibly ignorant, at least the way the Church understands it. To be ignorant invincibly means to (1) have not heard of Christ and His Church, and (2) to have no way of finding out about it even if you wanted to. Who meets those criteria now except some undiscovered tribes in the Amazon somewhere?
I'm sure there are a million other examples of how a minor exception is extended into a universal norm: the permissibility of girl altar servers, the abuses of annullments, dozens of liturgical issues, abuse of Natural Family Planning for non-serious reasons, etc. All of these began as concessions that were exceptions to a norm, and all have become the norm. The fact is that modern Catholicism seems to have an unhealthy fixation on exceptions and deviations at the expense of norms. The sooner we return to Tradition, the sooner we will come back to a Church who knows of only one way to interpret her documents and, through them, herself: and that is the traditional interpretation used by the Fathers and hallowed by centuries of use by saints and doctors.