Little in life is perfect. If an explanation, set of benefits or a case study about a past success sounds too good to be true, it probably is.
Ask for clarity. Long words, jargon and references to people you've never heard of suggest that the other person may be trying to punch above their weight. If they can't make their point in everyday language, they probably don't know as much as they say.
Take them on a tangent. A person who keeps on talking and doesn't listen may be worried that they'll lose the plot if they depart from their script.
Ask questions about detail. An interviewer was suspicious about a candidate who claimed to have worked in the past for a well-known advertising agency. 'Remind me, what number in Charlotte Street are their offices?' he asked. The candidate couldn't remember.
Ask for figures to support wordy claims. Even an approximation will give you a sense of what someone's idea of 'really popular' is.
Look for tell-tale signs of bullshitting. Expert bluffers are more likely to touch their face, scratch their nose, rub their eyes or touch their mouth more than usual.
Demand sources for all statistics. As Vic Reeves quipped: '88.2% of statistics are made up on the spot.' Ask where the data comes from, what assumptions have been made and what further information is available.
Watch out for over-friendliness. Listen to the alarm bells when someone gives you more compliments than you deserve (not always easy to judge).
Show some doubt. If you have any reservations, raise an eyebrow or offer a slightly quizzical smile. If they defend a bit too forcefully, you might have spotted a gap in their knowledge.
The Mind Gym, www.themindgym.com.