Perhaps since a portion of shoes, for example the top of them, are lifted from the ground then they count as being "on" the person? I can't imagine shoes would be that big a deal, but I am a bit braindead right now. And oh yeah, I'm totally squicked out by the Gollum example, but my treacherous brain jumped up like Hermione with answer just before I wrote "we have no example of a body part inside another etc. etc." and went "NO AVELERA WE TOTALLY DO" and the realization was followed by a full-body shudder. But you are right, it would make sense if it goes both ways but it's not NECESSARILY so. I guess I'd just go back to how the Ring changes size, since it's clearly trying to be effected by only 1 sentient Ringbearer at once? If it stayed Sauron-sized two hobbits could conceivably both wear it (uncomfortably) at the same time, by shrinking to their size it prevents that. Hence even if someone were topping enough to fulfill the rules of inanimate objects, the fact that they're living beings means they don't go invisible? Someone being carried off the ground by a Ringbearer would just appear to be floating, because they're a living person, and insertion would follow the same rule. The One Ring is one-passenger only (thank you very much, the Ring says haughtily. Ain't no Ring-threesomes for this old dame.)

As to the Ring's dormancy - wouldn't YOU tune out a bit after 500 years in a cave with Gollum? There's only so many solo riddle games and muttered conversations with "precious" that I think even an evil magical artifact can take before it makes a run for it. The next 60 years was just the Ring slowly waking up out and glancing around furtively to make sure Gollum is REALLY gone this time.

I'd also like to mention that I like the idea that, as an elven blade, the fact that Sting may not be wholly effected by the Ring is a very cool theory. It's like battle of the Elven smiths, whose hunk of metal is better.