The rapid and emphatic movement of Sarah Palin's left eye has become the latest sensation in the US presidential race. During the Republican governor's opening debate with her vice-presidential rival Joe Biden, she unleashed an apparently playful wink on several occasions.

For some voters, Winkgate was a folksy, intimate gesture. For others, it was a cheesy and inappropriately flirtatious sales pitch.

The link between a wink and sales people - and dishonesty - is well established. "Think of the used car salesman trying to sell you a car with 50,000 miles (but they rolled back the odometer from 250,000 miles)," wrote one blogger.

Winking when you are trying to sell yourself to voters is something else. George W Bush was criticised for fratboyish winks to the press corps and for winking at the Queen after a characteristic verbal blunder. The Queen was not amused. "She gave me a look that only a mother could give her child," smirked Bush.

Body language expert Judi James thinks Palin's gesture was not only deliberate but a useful part of her appeal as an "unpretentious" ordinary hockey mom.

"A wink is a very strong tie sign, which is a bonding gesture. Anne Robinson uses it to say, 'I'm a bit of a dragon but I'm nice really.' A lot of celebrities use it to connect with their audience and make themselves look down-to-earth."

But it depends on the winker. What's good for Palin might be disastrous for John McCain or Barack Obama- whose fist bump was previously the most discussed presidential-race body language. James warns that winking still has sexual connotations: powerful men who wink at work risk a sexual harassment claim.

Robinson, Britain's best known public winker, remains deeply unimpressed by Palin. "It's depressing that she exists, never mind that she winks," she says.