Polls are generally horrible. Self-selection bias, self-deception (i.e., what one perceives of one's self and what one actually does are almost always different and often wildly so), and self-disclosure bias (i.e., what one wants (others) to believe about one's self).
The entire analyst industry is basically built to do this. Of course, they tend to be ridiculously biased because they are getting paid so much for their opinions. Finding friends who work at places that already have the reports is one way to get them. :-)
In terms of actually useful data... Look for information about the users' and customers' actual behavior -- i.e., where the user/customer actually had to do something real like visit repeatedly, pay money, recommend you to other people, etc. As a number of folks mentioned at SUS, if you don't have information directly relevant to your play then look for various proxies and triangulate.
