If polls didn't have any validity, they wouldn't be used by every corporation and marketing firm, as well as think tanks and political candidates of every party. If you look at the better polls, they are done by independent research organizations, not those with a stake in the issue or outcome of an election. That's how the polls were conducted for the Star-Advertiser and Civil Beat, which by the way, advocated for stopping the rail project. 
It doesn't provide any benefit to pay someone to tell you what you want to hear. Independent research firms deliver findings on public opinion with minimal bias so they can be used for actual decision making. No reputable research organization does "push polling."