I thought skin pigmentation was a function of melanin content, and not necessarily blood vessels and/or flow -- though, like most parts of body, our skin reddens when blood is rushed in faster than it leaves, or if we're hot, or if we're excited internally. Maybe it's cause our skin is qualitatively different in our nether regions that pigment tends to, I dunno, "cluster" a bit better, thus making that skin seem darker.
My dick may be a bit darker, but it's not all that drastic a change. Now that I've spent some time of the sun, my body tones -- save for the tan lined areas -- match up pretty well from head to toe.
Heh, and even if my skin appears green on webcam -- ooh, Dee's an alien! -- feel free to check the rest of the photos. On the ones that were taken with a better camera, um, I'm pretty chocolately and I love it!
BTW, Kim, thanks for callin' me a beautiful bronzed brotha. Ha ha. You're still sexy, even if you are way more café au lait than me right now.