Understood and thank you for clarifying.
As someone who knows little about the accordion/concertina/squeeze box world, style and individuality is probably much more apparent to someone who knows rather than not. I can spot good vs bad I think - that's a mixture of technical proficiency and flow and rhythm and feel but nuances of style I wouldn't know. You might well know who is playing by their style whereas I would just hear an instrument played to a standard. A little like the best acoustic guitar player I ever played with I knew about 15 seconds after I first met him when he strummed three chords that he was really good. I can't tell you how I knew but I did.
It was more the singing with an accordion/melodeon/concertina (you see don't know the difference!) which I guess I have heard quite a number of people do when I have been to Whitby folk week and things around Hull etc