In Japan, I am told, if someone asks you to do something, it is considered very rude to embarrass them by saying “no”. Instead, you say “that would be very hard”, or “let me think about that”, or some other euphemism for “I will accede to your request when hell freezes over”.1
In the Republican Party, when the Democrats propose a bill, it is considered very rude to embarrass your party by saying “actually I think the country was doing just fine the way it was before Obama was elected, so I will vote against any bill you care to present on this issue”. Instead…
1 Finnish culture, I am told, has the opposite quirk: if you respond to a question with “yes, but…” the Finnish listener often fails to parse the part of the sentence that begins wtih “but”. Finnish-Japanese business negotiations must be a real adventure.