A player who is playing "scared money" is usually someone who is over his head or over his bankroll. He knows he's under-bankrolled for the limit or the game, but he plays anyway. Perhaps he's taking a shot after a solid run at a lower limit or he's desperate to score a win after a long losing streak. Players who are scared often play weak and tight, prone to seeing monsters where there aren't any. You take advantage of these players by constantly putting pressure on them with bets and raises. Isolating these players is often profitable.