I picked up an abused sharpmaker in the Cabelas bargain cave one day, just because it was cheap and my lansky was packed away in storage. Cleaned the stones with comet and put it to work. One of the 3 sides of both the fine stones has some irregularities that I can feel. I just don't use those "corners" when I am trying to get the best edge. What on Earth does a person do to damage these stones? I have no idea.
I can get a very satisfactory edge. Can't wait to try the ultra fine stones I have on order.
On a side note I carefully sharpened a 2 dollar Mundial paring knife to 30 degrees. It was laser beam sharp, but dulled noticeably after cutting an apple. I would love to examine the edge, before and after, under a microscope.