HOW can you tell when a politician is lying? His lips move.

Poking fun at those further up the imaginary tree than ourselves may the oldest form of humour in the world.

You can imagine slaves building the Pyramids sniggering when the pharaoh walks by. “He’s a bit of a softy, you know. He just wants his mummy.”

“What kind of animal never tells a lie?” asks the caveman. “A sabre-truth tiger.’’

There are far more bad jokes than good ones and I believe I’ve just proved it.

Politicians have always been jocularly linked to untruthfulness, but no more so than now.

I can’t recall, in my long life, much of it spent watching the steam coming from the politicians’ kettle, a time when those we elect to rule over us were held in more contempt.

A chasm is opening up between politicians and people, the like of which has not been seen since the time of rotten boroughs.

Our mutual contempt is almost palpable. We see them as free-loading, nest-feathering toffs whose pledges are worthless and whose word means nothing.

They, in turn, may see us as tax-paying fodder, ‘little’ people who can be bought with a penny or two on the pension or a few meaningless phrases like ‘big society’ and ‘defence initiatives’.

Being ‘economical with the truth’ forms the bedrock of our culture.

Take just a couple of examples.

The ultra-respectable financial services company Credit Suisse has just been castigated for advertising that its five-year savings packages could give you a 60% return.

Not a chance, says Which magazine.

So why advertise it? That’s naughty.

It’s about as naughty as Cadbury saying “only the flakiest, crumbliest chocolate tastes like chocolate never tasted before.’’

Oh yes? Does that mean the Aztecs were wasting their time? That for 500 years until 1959, chocolate tasted like rubbish?

Or “hands that do dishes can be soft as your face.’’ At least they have the word ‘can’ in there.

“ Why are your hands so soft, mummy?”

“Because I’m an unmarried 15-year-old, dear, with a face about as shapely as a baked potato.”

No cosmetic in the world is going to make a woman with a face like a baked potato look like Kate Moss, and it is, at least, partly the fault of the woman with the face like a baked potato that she refuses to accept her appearance and spends a small fortune on emollients and unguents trying to plait the proverbial fog.

I know that the producers of perishable goods have by law to put a sell-by date on their produce.

But I do wonder whether there’s a bit of a scam going on, the object of which is to get you to throw away the stuff you’ve bought and replace it with ‘fresher’ goods, whether or not the original has lost its taste and is now a threat to health.

This is, by any measure, cynical manipulation.

Advertising, though obliged by law not to tell lies, nevertheless bends the truth out of recognition. And we accept it.

Cars don’t make us sexier. The stains in the carpet do not entirely disappear. You cannot apply anything, other than perhaps tar, to make your eyebrow hairs thicker.

Politics is advertising. The politician will tell you his party’s policies are better than the next fellow’s, but everybody of voting age has seen that they aren’t and this is so fundamentally obvious you’d think we’d have difficulty pretending it was otherwise.

I think the problem most of us have these days is that anybody who believes something can scoop up enough facts to prove their point.

There are just too many facts about. Take, for instance, climate change. This implies global warming, but you can find any number of hyper-intelligent experts on both sides of the fence who will go blue in the face telling you it’s happening/not happening.

What is a person supposed to think? How can you get to the truth?

Maybe it’s not a welter of lies in which we’re drowning.

Maybe it’s that there’s just too much truth around.