->question wording,
->question order,
->day of the week and time of day a respondent is questioned,
->who the respondents are (adults, registered voters, likely voters, etc.),
->the number of questions asked,
->sample size,
->weighting required to "ensure" randomness due to high number of refusals to participate,
->weighting required to "ensure" "fair" representation of different political points of view.
At best, a group of polls taken over a period of time and averaged, might give an approximation of genuine public attitudes on the subject polled.
If that werew true, then Bush would have won in 2000 by about 5% and would have taken a number of states that went for Gore. I agree about the wording question order and all that, but Zogby is good. The sad truth is Zogby was right in 2000, Bush coasted on his lead and almost lost.