As a worship leader and musician, I know the difference between harmony and disharmony. When someone sings off key and when instruments are not in tune with each other, I notice and cringe.
Try as I may, it's hard for me to ignore disharmony. It distracts me and makes it hard for me to concentrate and focus on worshipping the Lord.
But when instruments and voices blend together in a harmonious way, the music carries me along in an uplifting flow of worship.