In twenty six years I have never had a client ask me to shoot a game animal for them unless they had already wounded it and felt they could not complete the task due either to jammed rifle (most common), being out of ammo, or could not keep up with escaping animal. Even then I would say those were less than one percent and their concern was with the wounded animal suffering more than necessary rather than collecting a trophy.
The vast majority of hunters are honest, sincere, hard working, ethical people. So are guides but a few bad apples tend to get all the press.