We know the doubling-strategy in any martingale-game produces sure profits – if only one had unlimited resources at hand. It seems there are other ways – although I don’t quite understand the exact procedure. Here’s an article from StraitsTimes (shortened) with the details:
“THREE foreigners were charged on Monday with cheating the Resorts World Sentosa of $13,400. […] [They] are said to have placed $3,600 worth of chips on a winning bet in a game of roulette after the result had been declared at the casino, to deceive the dealer into believing that they had won $7,200. […] [One of the foreigners] is also accused of trying to cheat a dealer into giving him chips valued at $15,700 […] by placing chips worth $400 and $100 on a winning number and between number 19 and 22 respectively after the result had been declared. […]”
Important to notice: this strategy is not a previsible process – no wonder it works! (the proof of that is left to the reader).