The theory – first advanced by Auberon Waugh – that a person has to be emotionally insecure, criminally motivated, or mad to go into politics has always seemed a touch on the harsh side.
Quite a few politicians were as normal as anyone could expect to be when they first stood for parliament. It was after they were elected that the problems started.
Who, for example, can have seemed a saner, more grounded candidate for public office than Chris Huhne?
Bright, ambitious, with a gleaming set of acceptable liberal values, he seemed, when he first started appearing on Newsnight, to be utterly sensible.
Eventually, though, there was the speeding-points problem, the affair problem, the 12-months-of-lying-to-the-public problem, followed by the eight-months-prison-sentence problem.
That sequence of bruising humiliations would be enough, one would think, to bring a person down to earth. After all, a spell in chokey transformed Jonathan Aitken from a strutting Tory grandee into a modest, slightly dreary chap with a God hang-up.
Huhne's peculiarity turns out to be more stubbornly ingrained. He went on the Today programme this week to talk about why politicians are distrusted. His conclusion was that it was largely Rupert Murdoch's fault.
Huhne recalled he was the only frontbencher to have had the courage to support re-opening the phone-hacking inquiry. After that, it was open season on him in the Murdoch Press.
This was not "straight journalism", he said; in fact, down the years, Murdoch had used his media influence to advance his own business interests.
While admitting his own responsibility in a briskly dismissive, I'm-no-saint manner, Huhne directed listeners' attention to the bigger picture.
Lying politicians were not the problem. The problem was beastly journalists and their unscrupulous employers.
Admittedly, Huhne had a product to sell – he has started writing a newspaper column – but anyone untouched by the madness of politics would surely have waited a few weeks before portraying himself in print as a victim of "media aggression". As it happens, the written version of his argument on Today is a masterclass in the art of special pleading.
There is the weaselly deployment of statistics (300,000 people have swapped speed-points, apparently), an economy with the truth (his jail sentence is represented as "two months in prison"), some boastfulness ("If I was not in parliament to speak out when I saw an abuse, why was I there?") and a touch of old-fashioned nastiness (his high-achieving wife Vicky Pryce is described as being "groomed" by the Sunday Times, as if she were a callow 12-year-old at the mercy of a paedophile).
It is not an entirely bogus argument. Huhne concludes that politics, which involves brokering compromises, invites distrust by its very nature and he is right. It is easy to sound off in the Press, or on TV – altogether tougher to get something done.
On the other hand, the argument that Murdoch has abused his power to advance his own interests is somewhat jaw-dropping when it comes from a former energy secretary who has just accepted part-time employment with a renewable energy firm. It is also a bit odd that this champion of transparency should refuse to reveal his salary for the new job.
Huhne has said that a future column will tackle the question of unfair sentencing suffered by public figures and it is at this point that a worrying thought occurs.
Could he be about to make a show of excavating events from his own eventful and often painful past, in the manner of angry confessional journalist Liz Jones?
One hopes not. That might just work for the career of Chris Huhne but, not for the first time, he will be doing considerable harm to the fragile reputation of politics and politicians.