I have to say, that is not a great example. Your earlier point still holds good that there is enough redundancy in English to distinguish these things.

Here "Isit?" means "Is it?" and that is obvious from the context.

Yes, that's true, but it's still ambiguous out of context, and the fact that it is also a direct response to what I said adds some unexpected humor so I give it bonus points for that.

It inspired me to come up with:

Fromwhereisitgoodideascome?