Many times i have read that some people offer something ,they are paid and then they don`t deliver the promised thing.Can these people get busted.I think this is not possible because there is not official (signed) deal,the police is not able to deal with these people.It is all about the trust,but i think there must be a way these scammers to be punished or at least their paypal account to be freezed !
most of the cases, you can not get anything back from online scamming. like KingofKings said you only can prevent it by being aware of the person you are dealing with and keep your record clean. check anything you can to make sure that person is trustable before you do the trade or deal. dont fall into their trap.