Special interest groups effecting public opinion

Yglesias writes,

I observed yesterday that even though agriculture subsidies are typically discussed as a canonical example of special interests controlling the political process, proposals to curtail the subsidies don’t actually poll very well suggesting a broader political problem.

I'm wondering if Matt really doesn't realize that the fact that agriculture subsidies are popular in polls is an example of special interests controlling the political process. His example is illustrative of the corrupting influence of large and wealthy interest groups on the democratic process. Far from being an issue separate from special interest control it actually represents a tangible manifestation of that control.

Trade associations and industry groups don't just focus their attention wining and dining Congress. They also spend huge sums of money in PR in order to enhance their public image and then use that "popularity" to leverage Congress.