I don't really understand your question; I hop the following will answer it:
At the time of which I speak, I had never heard of the SSPX. I was a travelling stranger, in a strange town, on a Sunday, looking for the nearest Catholic Mass. The nearest was something claiming "The Traditional Latin Mass", or some such verbiage. It also billed itself as Catholic, so off I went. (I was young, and foolish then). "The Traditional Latin Mass" turned out to be what we call the Tridentine Mass, which was vaguely familiar to me from childhood. Instead of preaching, the priest ranted about the evils of the Novus Ordo, that it wasn't a real Mass, and that anyone who ever attended it was committing a mortal sin by so doing. I spoke with a number of parishoners after Mass, who in a very self-righteous manner amplified on the theme. I discussed the incident with my Dad some time later, and found out what I had blundered into.
AB
I am curious as to how you discerned that by simply attending a SSPX Mass; or was it something else you wandered upon? I went to one SSPX Mass celebrated in an old hanger in Lake Worth, Fl. During his sermon, the priest spent the ENTIRE time bitching-out the Pope and attacking the Protestant fake Mass (normative Mass) with its invalid consecration etc etc etc.
The SSPX folks I know are the ones that have contacted me freq. in my area. They are riven with hate and among the most poorly-informed Catholics of any I have met. They read The Remnant, Catholic Family News and The Fatima Crusader as though they were the Gospels themselves and I have yet to meet one who has EVER read any history of the Liturgy that wasn't in an essay form penned by Michael Davies who actually thinks that Martin Luther was the first to desire a vernacular Liturgy. (I guess he hadn't heard of Pope Siricius).