According to new studies you can spot a 'bad man' just by looking at his face. Research into whether people were able to identify a man with criminal tendences (men who had been convicted of assault, rape and murder) showed a significant 'hit rate' of correct identification. (see Journal of Social, Evolutionary and Cultural Psychology)
The men had no identifiers (tatoos, scars, etc) nor did they sport a menacing look for the camera. There was also no way of telling which of the pictures were mugshots and which were not. Still, the average person seems able to recognise a criminal from a photograph.
Many reported that 'it was in the eyes' - others simply reported a feeling about each person they had identified but could not specify any one thing about their features which made them feel uneasy.
This opens up new questions on whether there are visual cues to underlying genetic predispositions - think of the stereotyped librarian, vegetaran or even paedophile (apologies for singling out veggies and bookworms). We often look at people and make assumptions about their lifestyle or background based on what they do to their bodies (piercings, clothes, make-up) but to guess a person's tendencies from their natural features is a whole different ball game.
If you've ever felt uneasy when working with a client for the first time, consider that you be seeing more than you think...