Tell Catholics/ "trads" you just meet your position on the new rite being doubtful/invalid?
That the NO 'mass' is a sacraligious abomination?
If you see someone with a divine mercy image do you go out of your way to tell them it's a false satanic deception?
I don't really do so. Only 1 person at my chapel knows my position on the new rites. I didn't want to come off as autistic and presumption and scare them off if i don't know them well. Is this prudence or cowardice?
It's not like they are automatically going to believe what i tell them, especially against their 'authority' figures.
I've told quite a few people who attend the NO and diocesan tridentine "masses" what I think about the new "mass" and the new rites of "holy orders". None of them really got upset at me. The only one who took it badly at first was a friend of mine, but now he's probably the one most convinced, if not the only one, and we've remained great friends. That might seem odd but "one plants, another waters but God gives the increase."
I've also told several SSPX priests, one of which in a very high position. They haven't denied me the sacraments. They haven't even tried to convince me of the contrary. One of them advised me that I don't scandalize the newcomers to the mission. I wasn't planning to do it anyway. It's not that I'm going to distribute brochures outside the chapel à la Jehovah's Witnesses.
The most important thing is to have the right intention when discussing these things. Do it for the love of truth and for the salvation of others. "Instructing the ignorant" is a spiritual work of mercy that we must all practice. There is a discrete way of going about this. Focus on principles, rather than on people. You tell them what you know about the new rites and let them draw the conclusions about Novus Ordo "Fr." X. In strong reactions towards these things there's always a personal component. "How come Fr. X who gave me my first communion in the NO is a layman?"
Show them studies and give them time to process them. Be patient. If they are stubbornly attached to their error and start attacking you, you just shut up and shake the dust off your feet.
You might want to avoid using the words "sacrilegious abomination" but tell them the whole truth in a way that they may conclude by themselves that the new "mass" is a sacrilegious abomination.
I believe we should talk more openly about these things, especially with priests and those in charge. It does not help anybody to just sit in the pew holding grudges because there's probably a layman holding a piece of bread in the altar. If it's God's will that they treat you like an "uncharitable sedevacantist" or leave you without the sacraments, so be it. The truth is more important than you taking communion today.
Do your part and tell the truth. Let God's will be done. If people are receptive to the truth, you saved them. If they aren't, God will use it to judge them, while you'll be rewarded.