There is entire tape comp from Sweden where every artists uses the speech, hah... Mostly it is not done in the obvious ways.
Perhaps that leads to question of sampling "wrong kind of" speeches in general. I am less annoyed by the content, more annoyed about the sound quality or something being too contemporary. Sampling current day political speeches, pretty much instant failure. Not because there would be lack of good speeches to sample from, but generally if it is sounding like you're trying to listen good noise and someone is watching the news from TV... pfff..