One curiosity of the Scottish referendum campaign has been that polls show that Alex Salmond is less distrusted than other politicians. For example, when Yougov asked "how much do you trust the statements and claims made by the following people?" they found that 40% of Scots trust him whilst 55% don't. For Darling, the figures are 34-60; for Cameron 26-70; and for Miliband 25-67.

I say this is curious because good judges have plausibly accused Salmond of sophistry and deceit, whereas the charges of outright dishonesty against No campaigners seem less grievous to me. (Of course, many No claims might well have been wrong - but that doesn't imply dishonesty.)

Why, then, are the No campaigners so distrusted? Part of the answer, I suspect is a halo effect; we tend to attribute all bad qualities to people we dislike. Whilst this is natural, it is, however, not logical. For example, my opinion of Cameron is so low that I could be mistaken for a Tory MP, but I don't question his integrity. Rather, I think of him as Wilf McGuinness thought of George Best: "You can rely on George: he'll always let you down."

Another part of the story is that the expenses scandal discredited pretty much all Westminster politicians. I fear, though, that inferring from this that individuals are dishonest is another example of failing to see emergence. The story of the scandal was one of stupid rules and procedures and peer effects, not (mainly) of individuals' corruption.

Yet another part of the answer lies in lazy cynicism. "They're all the same - in it for themselves", "why is this lying bastard lying to me?" Such commonplace cliches are anti-political not just in the trivial sense of being hostile to politicians, but in the deeper sense of failing to see that people can have different policies and values to you and yet be entirely decent and honest.

But, of course, we shouldn't just blame voters. What we're seeing here is a downside of Hotelling's law. For years, the Westminster parties have scrapped for the "centre ground" using the same top-down managerialist ideology. This means that the discrediting of some politicians discredits all: if you stand close together, it'll be easy for people to tar you with the same brush.

This error though, can be avoided. Werner Troesken points out that peddlars of quack medicines (pdf) prospered for decades. They did this by investing in advertising and product differentiation - often employing great musicians to do so - so that the failure of one product, far from discrediting others, merely led to extra demand as people looked for alternative cures.

And herein lies a reason for the comparative success of Alex Salmond and Nigel Farage. In distancing themselves from the "Westminster elite" they have (partly) avoided being discredited by association. In this sense, they are emulating snake oil salesmen. As for any other parallels, well...