But why would you 'say anything' about your heading if you are under your own nav; unless asked? The context was about whilst being vectored. "Heading 280" is the same meaning as "Radar Heading 280" so why use the word RADAR in that context
You're right, and I shouldn't, but can't help but argue (albeit less flippantly now). I think it's because all those years ago "Radar Heading" is what I was taught. I guess it is just stuck now.
However as a weak answer to your above question: "Position, Heading Altitude" was always a good opener, but I'll admit a VFR one. Somehow Radar Heading seems to satisfy a percieved requirement of a discrepancy (in my mind - but I'll bet I am not the only one). Also I'll report my heading (even if it is not an instructed radar heading) because I know you are about to tell me to turn right 20 degrees and report the new heading - and I can't do simple mathematics when I am flying, so it saves embarrassment later - you have to do the sums now not me!
Still, this thread is about pet hates, and clearly this is one for many controllers. That is indisputable.