Digital BW, The Print

I have been following all the threads regarding "Combing" and "Step-
Wedges" with great interest. I have been looking at there Histograms 
in Photoshop and trying to figure out what it was telling me. I have 
been seeing a lot of "stray" information in the Histograms that 
confused me, so I decided to try the following:-

1  I did a selection of just the wedge part of the published 
standard Step wedge by Jon Cone and MIS

2  I, via PhotoShop 6, drew a simple rectangle filled with a 
graduation from 0% - 100% grey.

Neither of the above gave me a "Clean" Histogram. I fully expected 
#2 to do so. I see lots of little comb teeth and a variation in the 
histogram height when I thought it should be constant.

Could it be that the "Combing" is something that Photoshop is 
introducing and does not really appear on our finished print?

I have also noticed that on the step wedge that those little white 
dividing lines do not appear between all the steps on some 
magnifications and not on others.

I am no PhotoShop expert, but the above seems a little odd, maybe we 
are all being lead astray by PhotoShop?

Barry