"a generalisation from one particular case, something that you do on occasions. "
No, unfortunately, many professionals were known as 'characters' who insulted audiences, farted around on stage, were notoriously late turning up, or when they did, arrives somewhat worse for wear - it was part of their persona and they were regarded as 'an act' rather than a singer or musician.
One of the worst tendencies was when people would pull out of a booking at the last minute, sometimes for the worst of reasons.
I was on the Singers Club committee when we were faced with replacing one extremely well-known singer who contacted us at the last minute to tell us he wouldn't be performing because he had been offered a more lucrative booking which he "felt he couldn't afford to turn down" - unprofessional professionalism, so to speak.
To be fair, this was not general, and it wasn't confined to professionals - the point I am making is that being a professional doesn't guarantee anything other than you have to pay them when they finished.
Many professionals were known for their reliability and dedication, but so were many volunteers who just did it for the love of the music.
It doesn't matter who chucks up on stage or where they come from - it is unacceptable behaviour and in the case I a referring to, a regular occurrence
Jim Carroll