Betsy was wanting a picture of twisted purl stitches in a discussion on the knit blogs group so, here 'tis:

--nice, normal untwisted stitches. The loop is lying in a relaxed way with the part that's on the front of the needle towards the right.

--twisted stitches. See (through my lovely new swallow casein needle) how the part of the loop that is to the RIGHT is on the back of the needle and the part of the stitch that is visible (ie, on the front of the needle) is pulled to the left?