I remember, many years ago, an announcement that there was to be a "test transmission" of colour TV.
People who, like myself, had an IQ of average or above realised immediately that this transmission would be visible in colour only to those who had already invested in a colour TV set ready for the advent of colour transmissions.
However, there was a woman of my acquaintance who insisted that the transmission would be visible in colour on every TV in the land.
I put it to her that, if such were the case, there was absolutely no point in buying a colour TV as one's ordinary black and white TV would pick up programs in colour when they were transmitted.
She saw my point to an extent but still insisted that the test transmission would be visible in colour to everybody.
She was, of course, a dickhead.