I, the Sponsor, and my partner, the PA, have received a PFL after his interview last month in Vietnam.. we have responded to the PFL a little more than 1 week ago and now beginning the wait to hear a response, now realizing it could be months or maybe a year or more.. the PFL listed a number of the IRCC interviewer's concerns, which have been completely addressed in our response. Some of their stated concerns were blatantly non-factual and purely conjecture. Other issues have relative case law supporting our situation. This is our second application (with the same Visa Office interviewer both times), and if it is refused, we will immediately file an appeal, and I feel much more confident pleading our case before IAD tribunal member than this individual. So we are very interested to see their response.
Obviously I've no insight into your specific case.
But yes - even though they put some reasons into procedural fairness (which they have to do in order to give you a chance to respond), some of these reasons
can be broad or vague enough that there is no specific part of it that can be called misrepresentation. Indeed, some are subjective, such that while one can provide more evidence in support of your application, it may not be possible to directly refute them.
So it cuts both ways: the claim is vague (eg concerns about intent to overstay) without any direct evidence of misrepresentation.
And while I'm not going to claim the legal background in order to name exactly what level of evidence may be required for IRCC to contend misrepresentation, I'm quite certain that it's got to be higher than "this person said they wouldn't overstay, I don't believe them, therefore they are lying."
No: misrepresentation requires some misstatement or omission of fact ('fact' here including the concept that it is possible to falsify the claim).* It also includes that the misrepresentation has to be material, and some degree of intent (and probably some other details).
Contrary to what others have said about a PFL, our PFL contained nothing suggesting that our application was being refused for fraudulent documents, misrepresentation etc.
Anyway sorry for the digression: but yes, to confirm, a PFL means that they expect to refuse you and that they are giving you a chance to respond. That does not mean that an inability to satisfy the officer
necessarily entails misrepresentation.
And another side note: even if the PFL did or didn't state this specifically, it doesn't mean IRCC can't decide there was misrepresentation. As an obvious example, if there hadn't been any before and then the applicant provided fraudulent info in response to the PFL, that would be misrepresentation, or if they subsequently discovered it, etc.
*This is a paraphrase, not the actual definition. And I warn anyone away from thinking too hard about intent, that way there be dragons.