What I meant by integrity was to have the results be more or less representative of the actual beliefs of an average site visitor.
I'm guessing some kind of statistical method for determining which votes don't fit the profile of a site's visitors combined with actively weeding out obvious instances of mass voting could make the results at least appear more accurate.
Sure there's no actual validity or rigor to online poll results, but the point is more to have results that at least appear plausible.
But then why bother having the poll in the first place? If you're just going prune the results so that they look like what you expect, you aren't really polling. You already know the answer, and you're going to throw out data until you get it.