Scotty's actually a HORRIBLE man!
From the first time I spotted the tribble, it's bugged me. Not that I have anything against tribbles; I love the little fuckers. It was the placement of the creature. When I saw it, I wondered how a fan as supposedly steeped in lore as the makers of this film could possibly have made such a mistake.
Here's what I mean - it's impossible. Scotty has the furball in a pretty little suspended cage on his desk, where it coos away. But the problem with tribbles is you can't have only one. Within a few hours, you either have lots of tribbles...or a dead tribble, since the only way to prevent their reproduction is to starve them to death. They simply can't stop breeding.
But jeez, everybody knows that! It was the point to The Trouble with Tribbles, after all. So just what the hell is going on there? How is it that Scotty has just one tribble, and can keep it in a small cage? Where are the other tribbles going?
And yesterday, when I saw the film again, I got a jolt of horror when I realized the answer - HE'S EATING THEM.
Think about it! Scotty is going mad because there's nothing to eat but those "dried protein nibs". Likely he's been feeling the effects of malnutrition, and would jump at anything that could vary his diet. How the hell he got hold of a tribble, I don't know. Maybe someone left it behind, maybe it crawled in to get warm. But it's alive, and that makes it a food source. Of course, with all that hair, there's probably precious little meat inside, but it would provide at least some nutritive value.
So Scotty's not the sweetheart we think!! I know it's gruesome, but really, how else can we explain the central problem - that it's impossible to have just one tribble?