It is so easy to target surveys that their validity is highly questionable. The same is true of "man in the streets" interviews.
I remember that coming out of the opening of the Monterey Bay Aquarium we were approached by a main stream news crew doing interviews. I was with my GF and another couple and we were sure they would ask questions about the new aquarium and how we liked it.
Instead they asked us how we felt about the death penalty.
2 of us were in favor, 1 thought they should be used for medical experiments to save innocent animals needles suffering and the other thought they should be locked up in solitary confinement for the remainder of their life with no human contact or entertainment and nothing to do but think about their crime.
But this was a liberal TV station and none of us ever showed up on the news show.
Obviously they thought that by targeting people who would attend the opening of an aquarium they would get people who would be opposed to the death penalty.
As others mentioned there is also the question of how a question is asked and what answers are available. They claim to use random phone numbers but they are often chosen from specific area codes where the highest probability is that you would get a particular socioeconomic group, people of a given religion, etc.
So, much like statistics, you can make them say almost anything you like depending on how they are applied.