Professor of Marketing at the Stanford Graduate School of Business, Baba Shiv, showed in a recent study, how "hypothetical questions don't merely measure our current attitudes: such questions can actually sway opinion and affect behavior." He explains the phenomenon of "push polls." This is when pollsters call up a voter and ostensibly asks for the voter's opinion but is really trying to push a viewpoint or agenda. The pollster can affect what a voter thinks about a candidate by posing hypothetical questions. The issue is these hypothetical questions bring up stereotypes in the voter's mind and can then taint what a voter thinks of a candidate.
"For example, if one of your stereotypes of politicians is that they're corrupt, then hearing a hypothetical question about a politician who took bribes will remind you of that stereotype, making you even less likely than before to vote for that politician in the near future."
Pretty sneaky, huh?