At a BBQ with friends last weekend we got onto discussing this question over burgers and snacks. Lovely dinner conversation and it’s still on my mind as some of the answers my pals were coming up with were quite strange indeed.
So, I thought of this place here.
Guys, can you help?
There are a lot of blood vessels in that general region, and I believe that they contribute to the color.
You have not seen enough anuses. The range of colors out there is much wider than you have been lead to believe. More research is necessary.
BBQ sauce?
Hmmm…
I’m still a “Guest” here, I’ve made maybe 6 posts.
Oh, well. Credibility be damned!
Mine is more of a light reddish color.
I use Charmin Freshmates. 
Is there really such a thing as anal bleaching, or is that just an urban legend?
Jenny McCarthy has a whole chapter (humorous) dedicated to it in her latest book. Bleaching is supposedly pretty popular in Hollywood.
Marge: You’re soaking in it.
Scumpup: Anal bleach?
Marge: Relax, it’s Proctolive.
Hmm. I figured It must be because of… you know… all the poop?
I’m blissfully ignorant of the color of my anus, but I can’t see getting it bleached.
Suppose the roots came back in dark? Wouldn’t that be a dead giveaway?
My Brown Eye Girl
She’s the one eye love
Generally the whole perineal region–Mr Happy’s knapsack, the external labia, the perianal area, and the skin in between, are more pigmented than the surrounding skin. Even when carefully scrubbed with lots of soap.
Certainly not universally true, but more often than not, I’d say. I’ve had occasion to view thousands but never thought to tally 'em up for color differential.
Gotta be related to visual cues somewhere in our evolutionary past but it’s kinda like asking why anything is different. Same deal w/ nipples and areolae; more visual than directly functional.
Don’t they give you a mirror?
No, a telescope. Never did figure that one out.
I figured this was done by the same method as by those people who pick out brown carpet for their homes. “Don’t worry Hank…if we get the brown, dirt will never show on it.”
I figured some evolutionary bit of brilliance had managed the same thing.
Then why didn’t evolution provide the same for cats? Or is it just that cats want you to look?
Absolutely. Why else would they walk around like that?
Hah! Ever try to get a good look at Mr. Dibbles’ turdcutter? Because you have some actual good medical reason to do so? Oh no, then he acts like you’re some kind of pervert!
And stick it in your face every chance they get…
You must have been one of the “bend over and spread your cheeks” guys.