Your analysis or Response Rates is quite accurate.
However, you do not mention the requirement of pollsters to meet every quota cell in the sample universe.
Therefore, if the pollster is conducting a poll in an area where 10% of the population is black female between the ages of 29 and 39 with a college, and living in a household making between 50 and 59 thousand a year, the poll is not complete until that quota cell is filled.
Polling in an accurate science and all you need to do is look at recent elections and you will see that most polls fall within the margin of error.
The problem with a sampling universe in this is far more complex than raw numbers ~ when you are down to a 9% response rate from the public at large you have to give up all those additional factors ~ else you'd have to call hundreds of thousands of phones, and when that happens the influence of respondents with multiple phone lines grows ~ which it may well have in Romney's case ~ (the rich have more phone numbers than the poor and middle class ~ and even then we found ourselves with 5 active numbers!).
The pollsters ~ who are not as stupid as we imagine ~ stepped back and began running what can only be called AUGURIES!
I think some of my original Freeper posts on AUGURIES are still accessible through Google.com by asking for FREEREPUBLIC MUAWIYAH AUGURIES.
Except for pre-selected targets I"m afraid random sampling polling may be a dying art. There are other methods that need to be brought to play.