Roy has made a good point. When your nuts are tight in their sack, it sticks your penis out and causes more of an indent against the fabric (bulge). When the nuts hang low and loose, so does the dick, causing less indentation. Wearing a pouch stops everything hanging low, so the bulge is more obvious, regardless of the natural hang of the balls.
This is me to a tee. I have low hanging balls so I get absolutely no push. When I have on loose shorts, there is no bulge!