They all make adjustments in their samples to try to make them more reflective of society at large. And they all follow different methodologies - you could have the same poll data show different things, based on how the pollsters tinker with the numbers.
All I am saying is that the reputable pollsters do not tinker to try to juke the stats. They try to get it right.
I know you won't believe this, of course. You probably figure that Soros runs most of our polling. Or the Trilateral Commission.