They definitely have a weirdly butt-squishing quality, as someone else mentioned.  I have what I consider a pretty insubstantial rear end (I'm 54 and weigh about 95 pounds, so pretty scrawny butt), and the horizontal seam that goes across the seat of the pants smashed it into two matching horizontal bulges.  You can imagine how great that looked.  On the other hand, the fit was on the tight side so the problem might go away if you size up.  These were size 1 and I usually wear a size 1 in Dickies.