The thing is, for me, as a controller, I would not be looking at the radar, with the intention of finding a skin paint aircraft, not squawking a code. I may or may not even see it, and if I did see it, without the transponder, I wont see any information, like call sign, type aircraft and altitude. Our rules said we could give a traffic advisory, if we were not busy trying to keep other aircraft from running into each other. Our choice, to give a traffic advisory, on an unidentified aircraft, was based solely on traffic, and the decision not to give it, was not subject to question by the pilot. There is so much clutter on a radar scope, that it is almost impossible to even see an aircraft that is not squawking an SIF code.
I am unable to figure out, why any controller would be trying to figure out what a raw radar target was, and why they would be asking other aircraft if they saw it.
As I said, I was not looking for UFOs. I didnt want to end up in a rubber room somewhere. 😀
I am a retired Air Traffic Controller and found you comments on issuing traffic interesting. I once asked my trainer, when I was first starting out, what is the difference between traffic advisories and merging target procedures? He answered, tone of voice.