Here's the money quote from the script formatting rules that cornbread ninja linked in the comments:
Some writers also use ALL CAPS when a sound effect appears in Action. Others capitalize important props. This would look like this:
MORTIMER groans and pops a handful of aspirin. The tea kettle WHISTLES. Mortimer pulls out a SUB-PARTICLE SUPER BLASTER and blows the kettle to smithereens.
In my understanding, this use of all-caps writing is meant to signify the introduction of a significant physical element into the scene. You can think of it as a way to mark the cues! Now, a lot of times a cue will be expressed by the camera focusing on the new element, whatever it is - so I understand why you might think that's what the caps means. But remember, a screenplay should generally avoid dictating directorial specifics like camera shots! Instead, it's just telling the reader, "something new enters the scene, right HERE." That might be expressed with focus, but it might not - for example, when the BLOODY BODY is first referenced, maybe the actual film will only show partial glimpses of it for a little while before actually focusing on it. Maybe they'll never focus on it at all.
At any rate, as far as I can tell using caps for emphasis in a screenplay is more of a good practice than a precise science with strict rules. If you understand what kinds of things need to be emphasized, and you feel like you're managing to emphasize those things with the caps, then your precise decision on a handful of cases you're not sure about shouldn't make a big difference one way or the other.