Hard to say!
Fun bumpers are thrown to reward a dog after running a tough blind in training or for exercise. No commands are givin so dog can do no wrong. High drive dogs with good work attitude are typically not givin fun bumpers as they cause more harm than good. A low drive dog or very soft dog that just recieved and handled a relatively high amount of pressure will benifit from a fun bumper!
I have a fire breather with a ton of bottem and a great work ethic, he doesn't need any fun bumpers the work is his reward. Flip side I am working with an Irish Water Spanial that is soft and lazy, he works when he wants.... If he works he gets a fun bumper as a reward. He is starting to work a little harder, applying pressure to this guy just sours him. I will take a fire breather any day.
Long and short....fun bumpers have no commands associated and no expected or required behaviors. They are all about sweetening up the dog! As a general rule of thumb fun bumpers should be avoided in training unless needed