I agree that coming in cold would be difficult to discern, but if you're used to watching stuff subtitled (or even without subs) you pick up on the subtleties of a performance through tone and inflection alone - even if you're like me and can only understand bits and pieces of it.
Really, it's possible to logic your way through something unless you completely fail to detect tonal and rhythm changes, or simply don't bother to understand how another language is supposed to flow. It's sort of like if you run across a word you've never seen before; you don't necessarily have to break out the dictionary to understand it because oftentimes the context in which it is used will give you a general idea of what it means.
So long as you know generally what's going on, a good performance will defy language barriers. Heck, even if you don't know what's going in it should elicit some sort of response.