A few weeks ago I found myself in a presence of a newly arrived American who was in the position of teaching a roomful of non-native English speakers. Her overly-punctuated speech was filled with false starts and hesitations, and she often clarified simple terms like "Senate" or "projector." Her words were spoken at such a slow rate that I began to fear that her highly-educated audience would fall asleep - or worse - form a generally negative impression of Americans. (Can you imagine that happening!)
Sarcasm aside, native English speakers often find themselves surrounded by groups of non-native speakers that can only communicate with them - and each other - in English. This puts native speakers at a huge advantage: They can concentrate on making a positive impression without worrying about verb conjugations or pronunciation mistakes. They can appear to posses an incredibly generous manner in helping others, improving the overall quality of information exchange. They may even feel guilty for their privileged position when they realize that in many parts of the world, for better or worse, English is the language of communication.
Of course, this can all go horribly wrong in one of two ways: First, native speakers may remain clueless about the abstract nature of their slang and head full-blast into an international conversation with "You look like sumpin' the cat drug in!" or "OMG, she like drank all my pop!" Even more sadly, they never seem to realize that they are speaking gibberish to those around them, thus isolating themselves from further social interaction other than small groups of hyperactive country-folk.
Second, we have the slow speaker, as was the case with the aforementioned lecturer. These individuals are so terrified of being misunderstood that they clarify every single word and phrase - only satisfied after the entire group is nodding constantly. Slow speakers also enunciate every word, and are acutely aware of any "foreign" term like "cell phone" or "bathroom." The problem here, of course, is that it can be extremely condescending to those who speak perfect and even not so perfect English. Are these types specific to the US? In my experience, yes - I think too many Americans have been raised in a purely English environment to really understand how to properly speak in an international one. At first, anyway.
I'd like to think I've found a happy medium. I was type two for a while, but I think I've succeeded in picking up the pace. But still, before teaching I plead with my students to stop me if I start speaking too fast. And as for my conversations with my fluent, non-native English speaking friends? I get a secret sense of satisfaction when I can trip them up. It doesn't happen very often - they're just too damn good.