If a poll doesnt give you the exact question they asked, don't even bother caring.
Some break it down and say whats the biggest problem in the country?(economy, national security, etc.) Then who do you think can best handle it?
Then they infer that that isa vote for that candidate, which is usually only done by the little crap polls.
Gallup is usually good, theyve been doing it awhile. and I think American research group is the other good one, i cant remember.
heres a good site with all the different polls
http://www.pollingreport.com/wh08gen2.htm
Avoid any polls that aren't telephone polls. Online polls and street corner polls only get the people that come by. But telephone polls also only cater to those that have a home phone, are home when the phone rings, and have the time to take the survey.
the key is random sampling, thats what makes the mathematic part work with the small population and the MoE. The best way is to take that random sample of say 1200, multiple times of different populations, then find the average.