The average person you'll find in a casino is playing honestly. But some ambitious gamblers come up with schemes to beat the house for millions. Although most cheaters get caught, there are others who manage to hustle casinos successfully ... until they eventually get caught too. Here are eight casino scams that actually worked.

1. Special Contact Lenses

Four con artists ripped off 64,000 euros (about $88,000) from poker tables at Les Princes Casino in Cannes, France in 2011. One of the cheaters (an employee of the casino) used invisible ink to mark the backs of playing cards—drawing a line for an ace and a cross for a king, for example—while the others used special contact lenses to spot the cards that would give them winning hands. Les Princes Casino grew suspicious of the players when they returned later in the week for a second round of high stakes poker. French authorities found the marked cards and noticed the cheaters' contact lenses after they ruled out cameras and infrared glasses.

2. Cigarette Pack Radio Transmitters

In 1973, a French roulette dealer at the Casino Deauville, along with his sister and brother-in-law, took the casino for 5 million francs (about $1 million). The dealer built a radio transmitter inside of a pack of cigarettes and a roulette ball with a small receiver inside. When a button was pushed on the pack of cigarettes, the ball could be controlled to land on a specific part of the roulette wheel. The cheating trio had a 90 percent accuracy rate with the scam.

The only reason why they were eventually caught was the casino owner was infatuated with the roulette dealer's sister, who was in charge of pushing the button on the pack of cigarettes. The owner wondered why she always sat at the same roulette table and made very low bets without winning. Along with his growing suspicion and heavy losses at the roulette table, he called in a debugging crew to sweep the casino. The authorities found the radio transmitter and tiny receiver, as they also caught the trio in the act of cheating.

A French film titled Tricheurs (The Cheaters) was made about the trio and its clever scheme in 1984.

3. Edge Sorting

Professional poker player Phil Ivey, Jr. was accused of cheating the Crockfords Casino in London out of £7.3 million (about $11 million) during a high stakes game of Punto Banco in 2012. The casino believed that Ivey used a method of cheating called "edge sorting," which is the practice of keeping track of the tiny and minor imperfections on the back of face-down playing cards.

Edge sorting works because some cards aren’t cut symmetrically. For example, a card with a diamond pattern on the back might have a half diamond on the top right and a quarter diamond on the bottom left. Ivey and his associate had the dealer go through multiple decks until they found one that was asymmetric. Then Ivey had the dealer rotate some of the “lucky” cards to make the sevens, eights, and nines more noticeable (going back to the earlier example, those cards might now have the quarter diamond on the top right). Once they found their lucky deck, Ivey had the table increased from a $50,000 to a $150,000 maximum. While Ivey claims that "there's a difference between increasing one's odds and cheating," British courts ruled that edge sorting constitutes cheating and sided with Crockfords.

In 2014, Ivey won $9.6 million at a baccarat table at Borgata Hotel Casino and Spa in Atlantic City, but the casino refused to pay him; the house believed that he used edge sorting to win.

4. Sector Targeting with Lasers

In 2004, three gamblers used a unique system of lasers and computers called "sector targeting," which calculates the falling descent of an object in motion, to correctly predict the part of the roulette wheel where a ball might land, hustling £1.3 million (about $2.1 million) at London's Ritz Casino. Based on the speed of the roulette ball, it's believed the players would secretly scan the wheel with lasers in their cell phones, which were connected to small computers, to determine where the ball might land. Although the system predicted the area it might land on, it doesn't predict the number or color the ball might fall on. The players would then make bets accordingly.

While the trio managed to take millions from the casino, they were arrested but ultimately not charged with any wrongdoing because there were no laws prohibiting the use of sector targeting at the time. Of course, it is possible that they were just using their phones as stopwatches.

5. Counting Cards

In 2011, Phuong Quoc Truong assembled a team of 30 card counters and blackjack dealers to rip off various casinos in Southern California. Dealers would pretend to shuffle a deck of cards, but they'd just put the corners together to make the sound and appearance of shuffling while actually keeping the cards in the right order for dealing winning hands. A signaler pretended to smoke a cigarette, but was really using a small microphone on the inside of his sleeve to tell an outside person what was on the table. Once the right cards were in place, the outside person would tell the smoker how to place bets, while the smoker signaled the players with his cigarette.

Sickwan Gaming Commission finally caught the gang, but not until after they took nearly $7 million from 25 different casinos. Truong and most of his accomplices pled guilty and are serving sentences that range from probation to six years in prison. Truong also forfeited his two luxury homes in San Diego, a Porsche, a diamond-encrusted pendant, and a Rolex watch for his part in the crimes.

6. The ATM Job

In 2012, ringleader Ara Keshishyan recruited 13 people to pull an Ocean's 11-esque bank heist on Citibank ATMs throughout casinos in Southern California and Nevada. The scam involved exploiting the security protocol on Citibank’s cash advance kiosks, which allowed multiple withdrawals at 10 times the amount deposited—if the transaction was made within 60 seconds. The scam would then result in hefty cash payouts from casinos. Keshishyan also instructed his gang to keep withdrawals under $10,000, so their illegal activities would not be reported to the government. The team would use the stolen money to gamble and thus have casinos give them complimentary rooms, food, drink, and entertainment based on their "high roller" gambling level.

Ultimately, Citibank noticed the discrepancies and alerted the FBI. The scammers were caught and faced up to five years in federal prison and a $250,000 fine. Keshishyan was ultimately sentenced to 57 months in prison and ordered to repay Citi the $1,045,585 he stole from them.

7. Counterfeit Coins

Louis "The Coin" Colavecchio successfully made counterfeit coins and tokens to use at slot machines at various casinos across the country. He used his ties with organized crime as well as his day job as a jeweler to make perfect dies. Casinos figured out they were being scammed when they discovered a surplus of tokens and slot machine coins in their vaults.

Colavecchio was arrested in 1998 and sentenced to six years in prison. In 2006, he was arrested when he started to reproduce fake casino tokens again. The History Channel made a documentary about Colavecchio called Breaking Vegas; many casinos now use special paper vouchers instead of tokens when players want to cash out of slot machines.

8. Roulette Scam

Ohio Casino Control Commission believed that 50 to 70 people were involved in an elaborate casino scam at roulette tables throughout the Buckeye State in 2012. The hustle involved players entering busy roulette games with bets as low as $1 and swiping casino chips while their accomplices distracted roulette dealers. The players would then go to areas in the casino that were not under surveillance like public restrooms to pass along stolen chips to other players, who would return to use them to buy more chips at a higher rate and cash out.

Scammers were caught in casinos throughout Ohio pulling the same gambit, with groups taking as much as $1000 to $2000 per job. Authorities believed that the group was based in New York City and hit multiple casinos in 18 different states. Many of the roulette scammers are still at large, while a small handful were caught and face strict penalties in Ohio, such as a $2500 fine and one year in prison.