I happen to look at men's pants quite a bit, in all settings.
When I am sitting in the bathroom, doing my "business," if someone else is in the stall next to mine also doing his "business," I will peek below the divider and seek out clues concerning the guy's pant situation. It may seem hard to believe, but it's actually possible to get a pretty good idea of a man's pants from this perspective.
Fabric can be noted very easily. Also certain details like stitching can be appraised. For someone very gifted like myself, I can even estimate the way the pant fits, the break, possible tapering, etc. Just like certain genuises can do ridiculously complicated math problems in their mind, I can create an accurate representation of a man's pants based on an 'under-the-bathroom-stall' view.
This guy's pants are not very good