All rolling is an illusion. It happens, but what we perceive when we watch a pigeon roll is an illusion, because the eye and the mind can't discern all the details. That's one reason that rolling pigeons always look slower on video than they do when viewed in real time, real life, with the naked eye. Slow down the rolling on a video, and even really fast, smooth, tight spinning will begin to appear loose or sloppy. And on slow motion video, the rolling that we normally perceive to be loose-sloppy can appear hopelessly ridiculous.
Some illusions for your consideration:
1. Dark check (Pensom called them "black check," homer men call them "velvet") self rollers look tighter and faster when viewed against a deep blue sky than do white-winged birds that are rolling equally tight and fast.
2. White selfs and light grizzles viewed against a cloudy, whitish sky look tighter and faster than when viewed against a blue sky. I once had a deep-rolling (40-50') white self Pensom cock that looked fabulous when rolling against a cloudy sky. When viewed against a deep blue sky, I could see him switch wings once, sometimes twice on his way down.