A con artist; someone who pulls confidence games; a swindler, scammer, huckster, hustler, and/or charlatan.
A manipulator or otherwise generally corrupt person who "games" a system, group of people, or other entity for selfish gains; especially of a political "sell-out" perceived as lacking integrity.
One who sandbags (misleads about his/her ability level in order to win bets); a hustler.
A robber who uses a sandbag to stun victims.