Personally, I think this thread has been helpful. I'd agree that we're never going to understand foreign perspectives perfectly... and as we get closer sometimes the chasm of understanding seems wider. Still, even cognitive understanding at a remove is helpful for having a model for dealing with misunderstandings as they arise.
As far as MacGuffin's issue with "how do you get the Fi-er to back off when they mistakenly think you feel X?" Let's look at it from each perspective.
The Fi-er
You, the Fi-er, have perceived emotion X (correctly or incorrectly) from the other party. The other party has told the you that you are mistaken. Ignoring minor misidentifications (target or minor feeling variation), there are three main options:
- The person is not feeling X on any level
- The person is feeling X and doesn't want to talk about it
- The person is feeling X, but isn't aware of it
So, in the context of the interaction I think it doesn't matter in practice (for you, the Fi-er) which of the above is true. You've already let them know they seem to be feeling X. Just pushing anyway is more likely to make the other person angry and defensive than anything else, especially if you are correct. So, saying something like (depending on the nature of the relationship) "okay, I'm sorry I'm picking up X from you mistakenly... I'll try to keep in mind you are not feeling X, but if I slip up or need reassurance that's the case, I hope you won't mind."
That way they know that you are taking their evaluation of their mental state seriously. Meanwhile, you can make a mental note and try to analyze why you think they were feeling X. It's possible it's just mannerisms or interaction style. It's also possible years later they will say, "I was so angry back then and so unaware of it!" Unless you are their therapist, it's not your job to get them to acknowledge their emotions—assuming you are correct in the first place. Some people have whole defensive systems build up around denying their anger or fear (for example)... forcing acknowledgement without laying a lot of groundwork first is likely to be bad for all parties concerned. And, again, you could be wrong.
The Other Party
So, you are the other party and this obnoxious Fi-er has just tried to tell you how you feel (like they'd know?!?). You are certain they are wrong, so how to get them to back off and leave you the hell alone...
Perhaps saying something on the order of, "I'm honestly, to the best of my knowledge, not experiencing X. If there's something I'm doing that is sending out that message, let me know so I can either try to explain or modify that behavior. Meanwhile, let's get back to doing [whatever you were doing before]. If you need a reassurance or reminder that I'm not actually feeling X (particularly at you), let me know."
So you've communicated that you understand that are perceiving something (something that isn't true, in this case), that it may be an ongoing irritant for them, and that you'd rather get back to whatever you were doing before. If they keep pushing, you can respond appropriately at that point, perhaps by pointing out how insulting they would find it if someone kept insisting they were feeling something they weren't feeling. (As Fi-ers, that'll throw 'em for a loop.)
Meanwhile, if you get the same feedback from multiple people ("you seem awfully angry"), keep that in mind. Maybe it's just your mannerisms or a specific behavior you could adjust (then you wouldn't have to deal with misreadings from obnoxious Fi-ers)... or it's not utterly impossible they are right on some level. That feedback is a data point (right or wrong) so keep your eyes open to see if a pattern emerges. If the only pattern that emerges is that Fi-ers are whacked... there's some truth in that, too.