If one collapses, and doesn't pump back up with oil pressure, they can rattle pretty good. Have come across a couple of cases where the lifter didn't turn, and the cam lobe would wear a groove in the bottom of the lifter, and they can make a horrible noise to.
On a lot of the CV engines, when you shut it off, you will hear a relatively loud tap when the engine stops, That noise is the lifters collapsing. I think if the compression release on the cam was broke, you wouldn't be able to crank the engine, without kickback, and stopping of the starter on compression stroke.