h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Well, I just submitted my "How to Have a Cow" article, I'd appreciate it if you'd read and comment
Today I'm supposed to go to work with my mom. She works at a summer camp place, and today is registration day, which will be really hectic so she needs my help. OK those are the boring details for today, now on to the good (read: freakish) stuff!

So a couple minutes ago, I was looking at my mouse...I'm not really sure why. I think I was just curious about it. Considering how much I touch it, I really don't look at it very often. Normally, this would be a very reckless practice...not looking at things before you touch them. But for some reason, it's acceptable behavior with computers.
Anyway, I was looking at my mouse. From my usual perspective, I can only see the left-click button and the wheel...the right-click button is obscured from view. The left-click button is pretty clean, so I assume the right one would be clean, too. Because of this assumption, I haven't given my right-click button a good hard look for quite some time.

I suppose that is how it has managed to achieve its current state.

Yes, folks, my right-click button has a 5-o'clock shadow. WHAT'S UP WITH THAT?? A dark grey smudge has decided to take up residency on my right-click button...and it's not paying rent, the scum. I'm not sure if any cleaning agent can rid me of this sludge!
After discovering this mess, I of course wondered how it got there. I like to keep my hands pretty clean so that these sort of right-click-button fiascos can be avoided. Obviously, I've succeeded in keeping my index finger pretty clean, since the left-click button is looking nice and clean-shaven. What's wrong with my middle finger?

And then it hit me. My middle finger! The forbidden, DIRTIEST of fingers. When rude people get angry, they raise this finger in the general direction of their anger's source. So does this mean that our middle fingers are actually physically dirtier than the other fingers? Do they produce more grease than most fingers, just as evildoers are traditionally "greasy" characters? Not being a rude person myself, the middle finger is not part of my personal repertoire. Even if I was rude, I don't think I'd use the middle finger, because it isn't terribly original, or even that scathing. I mean c'mon; how can you replace "You're a stupid git; a scum of this earth that should be wiped out with Tilex and a sponge" with "Here's the back of my finger. Don't I have a nice cuticle?"

But it doesn't matter what I think. Obviously, there is some truth to the idea that the middle finger is bad, since it is dirtier than my other fingers.
So now I'm starting to wonder: what about the other fingers? Is my fourth finger really the one most suited for rings? People used to believe that the fourth or "ring" finger had a direct link to your heart. Or something. Is my pinky finger really pinker than the others? No, it isn't. So why the name?

If anyone can answer these questions for me, feel free to!