Sorry if this is an obvious 101 question (I'm new here), but isn't there a difference between some of those examples?

I would also say that "how many grasshoppers are there?" has an answer that we simply don't know. But I can't think of "orange is superior to green" being true or false. I can think of ways that it could be better for a purpose (like if we're deciding what color the hunting vests should be), but not what the truth conditions of "orange is superior to green" would actually be.

If you're having an argument over school uniforms, presumably you're saying "Having a uniform will help this school fulfill its mission in X way" because you're trying to inform the other person's opinion on a particular policy. Is there a context where an argument over whether orange is superior to green is broader than "better for this specific purpose" but is about something other than subjective aesthetics, and is an attempt to convince one's interlocutor? (Nobody's going to say "You're right, I do find orange things nicer to look at than green things, although I thought it was the other way around until you pointed that out to me", are they?)

(This isn't meant to be an argument from personal incredulity -- I just can't think of a better way to word it. In fact, I'm not really trying to argue for anything, more like seeking clarification.)

Late to the party here, but:

Any English speaker who hasn't been brainwashed with prescriptivist poppycock will tell you that the sentence has two possible readings: one where 'his' refers to Martin, and one where it refers to Bob. In natural language, linear order or closeness tends to matter a lot less than you might think. (This is why many linguistic analyses represent sentences as hierarchical tree structures, and argue that the behavior of some word is predicted by its position in the tree.)

We can even see effects on the resolution of pronoun reference that apply across sentence boundaries:

Martin punched Bob in the face. He fell.

Martin punched Bob in the face. He was very angry.

There's a preference to interpret 'he' as Bob in the first case and Martin in the second (it's not absolutely impossible to interpret them the other way around, but there's a preference), and it comes not from syntax (we've kept that pretty constant) but from what we might nebulously call "the structure of the discourse". It's extremely hard to predict what the preferred interpretation will be in any given case.

However, I think that the example could have been better constructed for a different reason. There are actually two phenomena at work in the sentence: the deictic quality of the word 'left', and the problem of pronoun reference. The point could have been made with reference to either one individually. So it's not a very consequential confound, but it's worth separating the two effects nonetheless.

"Martin told Bob the building was on the left" still suffers from the problem that we don't know whose left is meant (Martin's, Bob's, the speaker's, maybe the addressee's?). In this case, I can't see any way of determining a definite answer, even one based on some word-counting bullshit.

There would still be ambiguity if we got rid of 'left' but kept the pronouns in:

Martin told Bob that the building was to the north of him.

('North' differs from 'left' in that it is defined relative to the entire earth, but the sentence has different truth conditions depending on who 'him' refers to.)

Or, with less grammatical awkwardness:

Martin told Bob that the Xbox was at his house.

Since "Either Martin told Bob that the Xbox was at his house, or Martin did not tell Bob that the Xbox was at his house" can be false if 'his' refers to Martin in the first clause and Bob in the second, it still fits the example, but the ambiguity comes from a different source.

"Have you stopped beating your wife?", as has been explained elsewhere, is simply an example of a question that has a presupposition. Linguistics grad students and the people who love them will sometimes answer "Presupposition failure" to questions, but this has yet to catch on in the general population. ;)