In the Free Reformed Church most all ministers and elders wear a black suit, or at least own one for those special occasions, such as Lord's Supper. I remeber going to my in-law's church, a FRC, where they had a black speaker cloth background behind the minister. The Rev. wore a black suit with a white shirt, and had a dark tie too, as I recall. I sat not too far from the back. During the sermon the minister kept disappearing, going in and out of blind spots caused by the background, and the way the lights played on it from my seating place. Its the other things that were not black that kept causing things to go in and out like that. At times all I saw was a white triangular shape, broken by a dark line, which was sometimes brighter than the white shirt: the showing part of the minister's shirt and his tie. It would come and go all of a sudden.
It was so distracting at times that I had to cease looking at him, and just look down.
When you talk about ministers in black suits, I am reminded of this. I've got nothing against black suits; but there's nothing unorthodox about having reservations about speaker cloth backgrounds, I would think.