Touche, but I think it is relevant in a small town where the barber may not have any employees other than himself; if he is good, he spends most of his time cutting hair, not sweeping up. Perhaps it is an unnecessary detail, but it still fits. You could make the riddle more confusing though if the good barber with a nice hair-cut had a neat shop as well. I don't know if you made the riddle up yourself, but I think that detail was meant to be a clue.