The priest is PRESUMED to have the correct intention so long as he does what the Church DOES - i.e., if he uses the correct matter and form, one CANNOT believe his intentions are amiss UNLESS HE CLEARLY AND UNEQUIVOCALLY DEMONSTRATES SUCH AT THE TIME. How could he do so? He would have to make a rather EXPLICIT statement to that end, etc. Even a FAITHLESS MINISTER, so long as he uses the correct matter and form, consecrates VALIDLY. Such is the teaching of St. Thomas and Holy Church. God speed.