Why is being Barack Obama much like finding the best strategy for a successful shopping trip at the pre-Christmas, credit-crunch sales? Because the following things are important: get there early; move fast; bring change. In other ways, however, Obama's methods are just not chiming with the culture of the coming recession. These are suspicious times, you see. Nobody trusts anyone. There are moles in our governments. Banks won't do as they're told. Coppers are knocking down our doors. You'd be crazy to take things at face value in these nervy, dog-eat-dog times. So full marks to the Republican congresswoman Ileana Ros-Lehtinen last week for her enthusiastic embracing of the culture of distrust.

The Florida congresswoman has not ended up where she is today by falling for just any charmer who claims to be the president-elect of the United States. So when she received a call on her mobile phone last week, and a voice announced that Mr Obama would like to speak to her, you can imagine her suspicion. After listening to the rogue for a minute, she cut him off dead – even if he was, she told him generously, "a better impersonator than the guy on Saturday Night Live".

The man called back again. And again. But it was only after a mutual friend stepped in and assured her that it really was Obama that Ros-Lehtinen began to lower her guard. After finally speaking to a laughing Obama, she reluctantly conceded: "Saturday Night Live could use a good Obama impersonator like you." Well, there's a career fallback for him should the whole president thing go belly up.

In this climate of fear, you have to admire the quick-thinking congresswoman for her attempt to stop a prank caller dead in his tracks. She was surely chastened by the embarrassment of her quondam leader, Sarah Palin, who chatted innocently to a Canadian radio station during the election campaign when somebody phoned her up and pretended to be Nicolas Sarkozy. "We have such respect for you, John McCain and I, we love you!" giggled Palin. "Give [your wife] a big hug from me." Nobody who heard her girlish disappointment when the comedian revealed the hoax will ever trust a cold caller again.

Jon Culshaw, the demon impersonator from Dead Ringers, should also take some responsibility for the culture of suspicion that is devastating our society. It's all very well phoning a chip shop and pretending to be Doctor Who – more surreal things than that happen to fish fryers every day of the week – but his call to Downing Street, pretending to be William Hague, for Capital FM, made the heart bleed for switchboard operators everywhere. Especially when this one explained kindly: "We do get a lot of impostors, you see." The office of Pakistan's president knows all about this.

Whenever big people call little people unexpectedly, from now on they are going to have to expect to be mistrusted. Only Gordon Brown is safe: nobody can gas about neoclassical endogenous growth theory quite as convincingly as he. But next time a world leader rings you during EastEnders, don't trust them. And if they claim to have any more than a passing acquaintance with your granddaughter, just hang up straight away.