1. Ask direct questions

Which can be answered by ‘yes’ or ‘no’. If you get a long-winded response then start to get suspicious.

2. Little in life is perfect

If an explanation, set of benefits or case study about a past success sounds too good to be true then it probably is.

3. Ask for clarity

Long words, jargon and lots of references to people you’ve never heard of suggest the other person may be trying to punch above their weight. If they can’t make their point in everyday language then they probably don’t know as much as they’re making out.

4. The person who keeps talking

And won’t listen may be worried that if they depart from their script they will lose the plot. Try to take them on a tangent and see what happens.

5. Ask questions about detail

An interviewer was suspicious about a candidate who claimed to have worked for a well-known advertising agency. "Remind me, what is the number of the Charlotte Street office?", he asked. The candidate, who had only temped there for a week as one of many short-term jobs, couldn’t remember.

6. Ask for figures

To support adjectives; even a range will give you a sense of what someone’s idea of ‘really popular’ is.

7. Expert bluffers may look you in the eye or may look away. 

They are, however, likely to put their fingers on their face more than usual, scratching their nose, rubbing their eyes or touching their mouth. 

8. 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 from this or other sources.

9. When someone is over-friendly

And gives you more compliments than you deserve (and that’s not always an easy thing to judge), listen to these alarm bells.

10.  If in doubt

You may want to raise an eyebrow or offer a slightly quizzical smile. If they defend a bit too forcefully then you could have spotted a gap in their knowledge.