I have been rebuilding / restoring complete, incomplete bicycles and frames from the UK, USA, France and Italy for well over sixty years and therefore I've almost a sixth sense as to what is "right" and might possibly be dodgy.
This Cinelli bicycle looks correct in detail and therefore I've every confidence that it is a genuine item.
I have never been sold a dud that I know of and perhaps generously, I do believe and trust the cycling fraternity.
I had never seen during the past decades, another brand of frame apart from Colnago, who used fluted tubes. I now know that there are several brands who have used fluted tubes, possibly from Columbus but also from others.
I have yet to be certain that Columbus produced them, I guess they probably did so but I can't find any record that they did. I'm presuming that they produced a modified SL tube set for the Cinelli which I have bought.
After purchase, there is no public record of an ebay sale but I have the details of this ebay auction recorded elsewhere, for reference if the bicycle is not what it has been purported to be.
Time will tell !
If anyone emails me and requests, I will send them a drive-side copy of the Cinelli bicycle photograph, which is one of several from the now dead auction site.