Yes, many pollsters do have a credible turnout model where they make phone calls and force the calls to conform to a D/R/I, young/old, black/hispanic/white model. Yes, they do exist.
But there are those who try to geographically weight their area codes by strictly population, ask a self identification of likeliness of voting and report the raw results, with no screen at all. BUT . . . they may ask the D/R/I question in the call and report it in the results. THAT would be bad were it D+10. I believe Gallup uses no partisan screen at all.
I would like to remind ppl in the context of this partisan mixture in samples thing that Romney’s pollsters thought he had an excellent chance to win right up to the final days. I think his official pollster had him ahead 1 pt.
His turnout model was wrong. Simply that. Wrong.