Generally to be a musician is also to be a general all round nice guy. But yes there are the exceptions. No names mentioned here, but I have a story of a couple of friends (fiddle and two row player) who went to a session which was tuned half a tone up. The fiddle could obviously re-tune but no option was left for the box player who just had to sit out.

Tuning up can happen in sessions where the locals keep getting swamped with visitors. I am not defending it by any means - but it does happen.