Yes, I have golf balls in 2 of the 3 boxes. I haven't put a roof over the boxes yet though and they do get some droppings in them. I think that is the problem, as well as having shredded paper in them. I know they are not too high since I watched a bunch of them easily hop up on the edge of the box. The top of the front is only about 16" from the shavings (at the most, I haven't measured it really LOL)
Granted, golf balls do work, but I prefer to use the wooden eggs you can buy in craft stores. They cost about the same (or cheaper, depending on the golf ball). I know the chickens don't care but I pretend they like 'em better too.