I am often horribly good at it about people relating to other people, but tend to get hopelessly confused when it's someone doing it in relation to me.
I have surprised people by the accuracy of my dissection of someone else's hidden motivations/purposes, but also by how unable I am to see it when it's me involved. And i only notice after i have got in a real muddle and tangle and somehow the other person often comes out seeming like the reasonable one because i'll have lost my rag, or got tearful, or resorted to "childish" avoidance strategies in order to cope.
And sometimes I think it does look like paranoia/over-sensitivity, and that is really difficult to deal with. I am so afraid of being mistaken, and "imagining" things. ( which i have been accused of) .
( Small digression on subject of not being believed: i heard an animal running around/thumping about on the floorboards in the attic the other night, and was way too alarmed to look myself. When i told the papa of my son, in the same room at the time, he thought i was imagining things, he had heard nothing, but it turned out i was right; two cats had got in through the open skylight and were chasing each other up there. He admitted to not having believed me. I admitted to almost not having believed myself, despite clearly hearing the soft thumps, because i have got so used to being told that i'm imagining things).