As far as licking the railings, my 4yo was basically doing that at WDW in February and was driving my sister nuts. Then Jake would lie down on the ground,..and that also made her wonder about him. He's my 4th child and I learned that I can't react to everything he does and had better pick my battles.
He is almost 5yo now and I'm hoping he won't be quite so touchy-feeling thos year.
The Clorox wipes aren't such a bad idea for the tv remote, but I don't worry much about the toilet since I do wash my hands after using it. Doorknobs are what I don't like to touch.
I know that I'm not a germaphob (far from it, I never even boiled my first child's toys, pacifiers, etc), but I don't think I'm too far in the other direction.
My guess, though, is that we all think that about ourselves.

(IE, we're the normal, average ones and the others go too far one way or the other...)
T&B