Twain's old saw has some validity, on the other hand, I don't think it makes much sense to expect a blizzard in Death Valley in July, with the average temperatures there registering in at about 40 degrees celcius.
many factors should be taken into account when evaluating the claims of polls, however, in polls administered randomly, with a high sample number, the statistical correlation between between the poll what the poll claims can be quite high.
I don't recall seeing one poll in the past year, whether painstakingly gathered, or done on the cheap, that shows segments of the American public supporting this war.