A Poor Performer CAN inspire another guy to 'Have a Go' , and the next thing COULD be Major ! but I agree its a pain if someone CONSISTENTLY is Crap ! We can ALL have bad nights - Fumble the Chords , lose a line of lyric - but be better next week .
After all , its all 'music' so lets have a bit of give and take , and perhaps take the guy who IS Crap every time on one side and try to suggest improvements to his act