OK. So in a Novus Ordo ordination, the intent is probably there, it's the invalid form, matter and minister which makes the ceremony doubtful?
Ah, you're definitely opening up cans of worms. So the question about intent in the NO (and there is a question of intent there also) has to do with the fact that normally when you intend to DO what the Church DOES, that which the Church does, aka the Rite, sufficiently expresses (at least outwardly) the intention of the Church.
When Pope Leo XIII declared Anglican Ordination invalid, he stated that the intention of the Rite was defective, and that the intention of the minister (their bishops) could not override the defective intention of their Rite, and that this was not changed by a correction they made to the essential form part, where they fixed the essential form but the entire Missal and the entire context for it and rationale behind it was so defective that it remained invalid even with this correction of the essential form.
Sounds a lot like the NOM, where initially they vitiated the essential form ("for you and for all") ... strangely, in every vernacular translation ... as if it were a coordinated effort (which of course it was). Then they "fixed" the essential form, but the rest of it and the context were still dubious, especially in their destruction of the Catholic Offertory, the chief part of the Mass that indicates what the intent of the upcoming Canon is. By itself, you could simply view the Canon as a re-enactment of the Last Supper, an "Institution Narrative" as the NO like to call it, vs. a sacrifice. With the original Catholic Offertory, that was absolutely clear. Not so much in the NO.
Similarly for the NO Ordination, there's hardly ANYthing in the NO Rite that has any mention of the Catholic notion of priesthood (whereas the Traditional Rite was filled with it).
In any case, I hold that the NO Rites, including Ordination and the Mass, are so vitiated in the intention expressed by the Rite that the minister's intention to do what the Church does cannot override it.
Now, the SSPX line has been that the intention of the Rite is ambiguous and there's no Catholic intention unambiguously expressed anywhere in it, and so the validity depends upon the intention of the minister being correct and his correct understanding of what the Rite SHOULD intend (even though it doesn't do so by itself). I disagree and find that this contradicts Pope Leo XIII on the Anglican Orders, because the Pope taught that an internal intention of the minister to do what the Church INTENDS to do in Ordinations does not somehow supply for or override the defective intention of the Rite. He didn't say that, well, we should investigate each bishop to see if he believes correctly about the nature of Ordination to determine on a case-by-case basis whether it's valid or not.
But, yes, the NO changed essential form of Ordination to Priesthood and Episcopal Consecration to the point that the essential forms are also dubious.