I think Don sums it up perfectly, it won't work all the time, no call will! BUT it worked perfectly for me a week ago on the farm in KS. I was hunting a fields edge, where there was several scrapes made, and I was in a stand about 15' in from the fields edge in a creek. I had tried some rattlin', no luck. The "can" is a call that I mainly use when I can see a deer. I've had mixed results. BUT, on this evening hunt, just before sun down, I spotted a buck crossing the field, not coming to me, but his course was going to take him 100 yards from me. I quickly pulled the can from my pocket and flipped it once, he turned his head like he heard it, but he never broke stride. He was walking quickly, like he had some where to be. So I again flipped it and this time he stopped right in his tracks. I waited only a couple of seconds and flipped it again, BUT I only kept the hole plugged for about a half bleat! He came at a gallop. I quickly stood and readied my bow. He got to the edge of the tree line/creek and started following the edge to me. I drew as he neared the first of two shooting lanes. To my dismay, he turned and entered the shooting lane and stopped, facing my direction at 15 yards. There was a small, but loud, little voice that convinced me to wait for a better shot. He only stood there a few moments before he moved on into the creek, looking across the creek trying to located the doe that he thought he heard. His path took him past me stand at8 yards, and as he got just beyond me, he stopped giving me a simple 10 yard shot, and I drilled him. So, for me, I have had luck with the "can" BUT this is the first buck that I arrowed because of it.
One of my brothers was hunting just a couple hundred yards from me that same evening, he also called in two very young small bucks with his "can", BUT he failed to call in a mature buck that he saw. So, there again, it worked for him, just not on the big buck that he saw.