The most peculiar thing is when someone seems to have an interest to grow, to build a meaningful contact, maybe a friendship.
This person may show intelligence, even talent, he can have valuable insights. He can write, he can listen. He seems interested to investigate in that particular field, he can even come up with relevant feed back, – to cut it short – , you seem to have reached a consensus, when bum! – out of the blue you understand that the words of his person meant nothing, that the discussion meant nothing, that you have given precious time to an unsound insidious jerk, who has misused your time and your trust, and there you are again – left alone, suspended in disappointment, in the hollowness of his mendacity.
These impostors are more dangerous than average ignorant people.
They are very shrewd and can display a wide range of great qualities – talent, deep emotion, empathy, even love…It all can seem true and real, they are great masters of dissimulation, managing incredibly well to hide their being a fatal fraud.
You may want to read this as well:
http://julienmatei.com/2011/12/13/watch-out-for-false-prophets-2/