I do think it's easier to see wrinkles on some heads more than others. I found that shining a light on an angle at the head helps you to see them pretty clearly.All that said, after using this method on my 6" toms, I'm no longer convinced that it even works. I can't even see the wrinkles in the beginning stages of the procedure.
Having said that, I used the method, and I think the rack tom turned out fine, but I didn't like the floor tom...though I suppose it was fine.
Went back to my tunebot.