I was talking specifically about writing, not speech. In speech the problem of contracting "is" with nouns ending in "s" might arise, but in writing the structure and the meaning of the sentence becomes apparent.
These problems don't appear if the sentence is read, as opposed to spoken. And even if it was spoken, how can the listener interpret "'s" other than "is"? Hearing that ""s" as something other than a contraction wouldn't make sense logically.
Is that confusion present in "Talking to James's a total waste of time"? If it were, one could just add some context as in "James is one of my co-workers. Talking to James's a total waste of time. He always argues with everyone for no apparent reason and never admits it when he is wrong."
How is "That dog's barking too loudly" different from "The house's on fire" and "Talking to James's a total waste of time"?