You *used* to know what you were getting whenever you called "an SSPX priest". As in, they had the same training, so despite personality differences there was a certain foundation, a certain low-water mark, a certain minimum knowledge and competency that ANY priest in the organization would have.
The seminary formation itself has changed in the past 15 years, and that is grave. That means that you have a variation now among "SSPX priests". So you have to sort and sift them, based on their date of ordination, personal reputation, word of mouth, etc.
That is the sad truth.