Would it ever be possible to "annul" an adult baptism?

I was thinking of this passage in the Catechism:
In the case of a non-baptized person ministering the baptism, I'm guessing that the Church must be present in some extraordinary way that transcends time and space, which is only possible through Christ.

If the person being baptized is unconscious or otherwise not able to act on his/her own, I think we are presuming that the person would desire baptism and assent to the faith ("I believe"), if only he/she were mentally competent and aware of the urgent circumstances. We have reason to hope that God can give the person the opportunity in some supernatural way, along with free will. If the person desires, assents, and receives the Holy Spirit, it's all good. They are free to reject it though, and they might. Here on earth, we wouldn't know if the baptism actually "took."

Now suppose the person survives and makes a full recovery, and it turns out they never wanted to be baptized and still don't want to. Our presumption is proven false, and there was no baptism. We could think of that as an annulment.

My takeaway from this, and we may be talking about the exact same thing, is that baptism by a non-believer is always valid, just that it can be reasonably foreseen this wouldn't happen except in a case of necessity.  Therefore Our Blessed Lord wouldn't "pull out all the stops" and allow His Church to be present, as you put it, in these circumstances but only these circumstances.  As a practical matter, non-Christians wouldn't be going around baptizing people willy-nilly --- it would be, for instance, a non-Christian military chaplain, or a non-Christian worker in a Catholic hospital, doing this for someone in extremis who could reasonably be foreseen potentially to desire Catholic baptism. 

To borrow an example of military chaplains performing rites of religions not their own, I'm assuming the producers of MASH weren't just taking literary license when they depicted Father Mulcahy performing a Jewish bris (don't recall the exact details, one hopes there would have been a little more surgical expertise than that , perhaps a surgeon actually performed the operation while Father Mulcahy recited the ritual prayers). 

I hope the rest of the world can see, aside from being uncompromising on marital and sexual matters (because she cannot do otherwise), just how much the Catholic Church "bends over backwards" in the post-Vatican II era, to accommodate other religions.  Do you think, for instance, that someplace like Bob Jones University would ever make its worship space available for a Catholic Mass or a Muslim service, if a group of Catholics or Muslims needed such a space?  "When pigs fly" is probably an apt metaphor here.  We make all of our social services, and things such as sponsoring refugee families, available to everyone regardless of their religion, with absolutely no expectation that those people will convert to Catholicism or embrace it in any way.  We'd be happy for them to do it, but it's never expected.  I knew of one Ukrainian Byzantine Catholic mission that was having a hard time getting started up, because the Ukrainians in that city had been assisted in coming to the US by Baptist groups, and, well, the Baptists had browbeaten them into going to Baptist services, rather than retaining their Catholicism.  Dirty pool if you ask me.

We take pains to assert that goodness and truth can be found in other religions.  We inculturate everything we possibly can.  Does any other religion do anything like this?  Are Hispanic people allowed to retain any aspects of their devotion to Our Lady of Guadalupe when, regrettably, they become Baptists or Pentecostals?  Are Christians allowed to retain any attachment whatsoever to the rabbi and teacher Jesus when they, tragically, abandon Christianity and adopt Judaism? 

That's why I wasn't nearly as rattled as some orthodox, faithful Catholics by the whole Pachamama brou-ha-ha --- I reasoned "well, evidently this is just one more instance of inculturation, a little ambiguous to be sure, but not 'idol worship' by any stretch of the imagination".  It seems as though most cultures in the history of the world have closely associated the divine with the concept of a "mother goddess", a tendency that I called "atavistic" on another forum, a term that was disliked by one reader (can't account for that, "atavistic" is more of an anthropological term, not a pejorative one in the least, guess that particular word just hit some sort of nerve), and the Catholic Church was able to reach these people by relating the Faith to something they already had.  Put another way, it's just part of the human condition to "cry out for mama", and ancient religions have reflected this --- Lakshmi, Isis, Astarte, the list goes on.  Marian devotion fits this like hand in glove, and Lord only knows the countless people who have been drawn to Our Divine Lord through devotion to His Mother.  I know the Jack Chicks of the world don't much cotton to this, but we were not put on this earth to cater to such folks, we were put on this earth to bring other souls to God, whatever form those efforts might take.  I taught my own son about the archangels by likening them to the comic super-heroes he has always been so fond of.

Yes, that is true, as long as the baptism was valid in the first place.

If the baptism was invalid --- for any reason --- then no baptism ever took place, appearances to the contrary notwithstanding.  No baptism, no mark.

And just to clarify, when we say "invalid", we are saying "no sacrament, it didn't 'take', nothing happened".  This is to be distinguished from "illicit", meaning against Church law or discipline, done when it shouldn't have been done, prohibited, but still valid.  Sacraments can be illicit without being invalid, or they can be both.  "Licit but invalid" is not possible.

If it were an objective point of fact, such as the misguidedly communitarian "we baptize you..." used in some baptisms in recent years (quite illicitly, I would add), as in the priest who was in the news a few months ago who had, in fact, never been validly baptized, there would have to be some kind of testimony such as a videotape (which is what the priest used).  As far as I am aware, if one priest poured the water and another priest recited the words, that, too, would be invalid.  In the absence of video recording, you would probably have to have multiple affidavits from witnesses, which would all have to agree on how the baptism had been done. 

If it were something more subjective, such as "I was comatose, the nurse baptized me, but then I woke up, found out what had happened, and had always told everyone, in no uncertain terms, that I would never agree to such a thing, I don't believe and I don't ever want to be baptized", or if it were even fuzzier and more subjective than that, "they rushed me through the catechumenate, never brought up Issues XYZ, and if I'd known all of that, I would not have wanted to be baptized into the Church", well, that would be a lot more difficult to prove.  In the case of the latter, I'm not sure the Church even entertains such objections.  The threshold for valid baptism is fairly low, otherwise, all of the material (i.e., unsuspecting and in good will) heretics who become baptized Christians while having an imperfect understanding of what baptism or the One True Church even are, would have been invalidly baptized.  We know that the Church accepts most Protestant baptisms --- something about which I have at least a small quibble, in that these baptisms are frequently conferred very sloppily, the minister saying "...in the name of the Father, the Son, and the Holy Spirit...", not "and of", with the person being immersed only once after the words are said, not during.  That said, if the Church accepts it, then so do I.  I am not the type of Catholic who says "let's take each and every teaching, 'run it up the flagpole of wonderful me', see if it flies, see if I believe it, and if I don't, well, then, what I think trumps what the Church says". 

Some ostensibly Christian baptisms are regarded as invalid (Plymouth Brethren, Shakers, Salvation Army et al) while others are regarded as doubtful (Seventh-Day Adventist, Mennonite, Moravian, et al).  The baptism rites of the Jehovah's Witnesses and Mormons are also invalid.  Mormon baptism uses the exact same words and immersion, as Christian baptism does, but they interpret those words radically differently enough, that it invalidates the baptism by intent.  Not at all clear what is doubtfully valid about baptism by Mennonites and Moravians.  I was also of the impression that the Salvation Army was basically another Protestant denomination (though with a strange method of organization), but perhaps not.