why did the pearl cause dishonest people

The dishonesty illuminated in people after the pearl is discovered is directly related to one thing..... greed. Kino's desires are marked by what the pearl can afford him; the pearl agents are driven by the prospect of money and collectively cheat in order to garner the price most advantageous to themselves; the doctor doesn't care for Coyotito, but he's willing to put himself out to attain what Kino has found; the people are jealous, and it drives them to violence.