OpenSecrets.org hosts a long-running effort to correlate the rate at which legislators favor or oppose particular industries with the size of the contributions they receive. Turns out, they track very closely. Like, to the point where reasonable people stop thinking "correlation" and start thinking "causation."

That's a very important point in public corruption debates, since there mere perception of corruption can diminish trust in public institutions. And trust, as it turns out, is their greatest asset. That's why effective anti-corruption laws are written to prohibit actions that simply appear corrupt, along with those that can be proven corrupt beyond all reasonable doubt.

When it comes to public trust, appearance really does matter.