Thank you for the thoughtful and courteous reply.
I have only been to one SSPX mass. Most of what I think I know about them, I learned here, so I will defer to your superior knowledge of the people involved.
I am only trying to deal with troubling issues; I have no emotional investment in defending the SSPX, nor, as many here seem to have, in painting them as villains.
That said, I want to reply to a few specifics in your post.
"The word "heresy" has been used with astonishing frequency in connection to the person of the late Holy Father."
There are, I think, several troubling things. On this forum we have often been treated to pictures of the late Holy Father kissing a Koran and presiding at a Mass where the "lector" is a well-endowed woman with her udders hanging out.
Two other troubling questions are, why did he succeed as a cleric under the communists, and why didn't he don a flamethrower and burn the homos out of the seminaries and the priesthood?
Charity, as you may have divined, is not my strong suit, but to extend a bit of it to people who call that "heresy," don't you think they may have a point?
"I would argue strongly that is manifestly inferior. But that is not the same thing as rejecting it as heretical and invalid."
Suppose a person were out to hurt the Church. He needs to show some restraint, lest his motives become too obvious. Therefore, instead of introducing temple prostitutes and drunkenness as features of the mass, he merely introduces a manifestly inferior mass that, while valid, will nonetheless result in many souls being lost, because as spiritual food it is simply inadequate. Is heresy the wrong word for that?
"A pope who orders you to sell church offices or demand money for the sacraments should indeed be ignored and even publicly denounced."
What about a pope who sends you bishops who send you predatory homosexuals (sorry for the redundancy) for priests, and insist on women lectors, altar girlies, faith-killer ditties instead of the magnificent music of the Church, wreckovation of lovely Churches, clown masses, invalid matter, liturgical dancing, and on and on and on...
What about a Holy Father who gives Phoney Mahoney a red hat?
You can argue that he didn't know. I would reply that he had a responsibility to know, and that the Holy Spirit would certainly have helped him find out.
"unless obedience to the order would constitute a grave sin or a danger to the faith, one should still obey it."
You're right. But many of us feel that we are on the horns of a dilemma. On the one hand, who am I to challenge even the humblest parish priest? On the other, there are things that seem to cry out to be challenged.
Frankly, I think that many of the masses I've attended have constituted a danger to the faith.