Do they have a lead core? What keeps them from just floating like a bobber? I used to have a hand carved fish decoy that was used for spear fishing and it had a lead belly. It was made by a guy with initials E.P. I think his name was Earl Price but I can't remember now. Im not sure what ever happened to that thing.
I'm not sure of the lead bottom on these lures, but I do know that they used different amounts of lead for depth control. The spook is more of a top water so if there is any in it I don't think it's much.