My understanding is chamois always next to the skin... no seams you see

And as for guys wearing tights under shorts - never seen it here... the seam of the tights against the seam of their skin makes for wicked discomfort. I know of no serious male road cyclists (dunno about mtn bikers) that have anything but chamois next to their skin down there...

And me? I always wear tights over shorts if I'm not wearing my tights with chamois in them