Why:
do mudcrabs carry forks?
or lockpicks?
or gold?
Because they were planning a dinner banquet. You were supposed to be the main dish. The fork was from the exceptionally fastidious one who is fearful that the kitchen staff didn't do a good job of cleaning up after the last banquet. The lockpick was carried by the Boy Scout just in case you decided hide from them behind a locked door and the gold was the considerate one who always feels guilty about stiffing the waiter.
vampires carry silver weapons?
Because iron and steel weapons are soooo last year. All of the really in-people are carrying silver this year.
do Dremora carry potions of the sea? In Oblivion? (Like they're planning to "breath under lava" or something?)
It's actually Oblivion cocktail sauce. It just works like a water-breathing potion on Tamriel. They'd have been dipping their Oblivion shrimp at the next office get-together if you hadn't whacked the guy. You really ruined a lot of keggers by sticking your nose through those gates, you know.
What happened to that Guard's ear?
The guard dropped his bling and it's looking for the dropped earring. It'll be back when it finds it.
How do the psychic guards who know that a particular apple was stolen:
still miss one lockpick?
They didn't want to fish it out of where you stuck it. Ewwww.
don't notice that you're the missing prisoner who was the first escapee from the Imperial Prison in 40 years?
Because of the facial reconstruction done in your cell. The Emperor is the only one who recognized you and he's dead.
don't notice that you're carrying the one item absolutely necessary to the survival of Tamriel, a great huge mucking ugly amulet no one could miss?
It's probably with the lockpick. You can't wear it, remember?
For that matter why does Harrow:
never take away the dagger that guy who turned up at your bedside and told you to assassinate some guy at a cheap hotel gave you?
It, too, is with the lockpick. Freud had a few things to say about it. There is counselling available for that.