"To my mind, I asked a very reasonable question, and have said nothing that is not being said daily in the media here in the UK"

Your question is "dubious" because it is not really a question, it is an editorial comment on how you view America--it is a weakly veiled way of saying "How can you have an African-American President when you're all such racists?"

Your question is "dubious", because for anyone who is paying attention, it has been answered already. If America weren't ready for Obama, 17.5 million people would not have voted for him already in the primaries, and he wouldn't be he is right now--

Finally, your question is "dubious" because your country faces the same, and perhaps even greater issues related to the inclusion of ethnic/cultural/racial minorities in government, and starting a discussion about whether "American is ready..." is a way of pretending that you are above and beyond it all.