[Stultis]

It is unfortunate that these polls don't limit the participants to those who have a demonstrable knowledge of American History and the Presidency. Lacking that limitation the 'Poll' ends up being, for the most part, a name recognition exercises, useless in measuring true greatness..

Well, sure, except you know that Gallup is never going to release a poll that says, "Clinton Choice of Ignorant," nor would the Times, etc print it nor CBS, etc broadcast it.

I have often wondered about the point you raise, though. Are they any polling orgs, or any circumstances, where qualifying questions are asked to measure the relevant knowledge of respondents?

[drt1]

They have targeted surveys, most often used in Market Research, that 'Qualify' respondents. This technique is used often whereas this type of survey is just for publicity or to prove a pointless point IMO.