Surveys are a bunch a bull, I get republican ones all the time, and the only reason I get them is I have a free membership to limbaugh. So they mail to all of his listeners and then act like it is a balanced result. GOP has theirs, Dems have theirs but none of them are accurate. If you poll 1,000 people in MO, KS, AR, IL and Iowa and then poll 1,000 in MA, NH, ME, NJ and CT you would get completely different results. Polls are useless
There are rules for how to conduct surveys.
You make some very good points, there are a lot of bullshitters out there that doesn't take the necessary steps that are needed to produce truthful survey results.
However, survey institutes are generally pretty good at this. Why? Because it's their business idea to be as accurate as possible.
If they're able to give survey results that give a truthful illustration of how Americans feel about an issue, that is good business for them.
So in order for surveys to be truthful, the are usually conducted throughout the country, and on a demographically widespread group.
But this is mainly the serious survey companies, and universities.
You still raise a very valid point however. Those surveys you're asked to fill in, they're probably also used to scan the Limbaugh audience, know how his audience has changed their opinions on the topics that Limbaugh discusses on his show, so he more easily can address his audience.
My best advice to you would be to either send it back blank or fill it in randomly.

-Hedge