The players are short of money and unhappy. Perhaps they have big debts. Perhaps their careers, which once promised so much, are petering out into nothing.
Whatever the reason, they are easy prey for match-fixers, who are now so rampant they are believed to operate in nearly every Asian football league, from Singapore to South Korea and most countries in between.
"We're not talking about (UEFA) Champions League or the World Cup finals or anything like that," said Britain-based Scott Ferguson, a consultant to the betting industry.
"We're talking domestic-level games where they're on a fairly mediocre wage. When someone comes up and offers a couple of grand (thousand dollars) to do this, their ears prick up."
The operation is simple: approach a player or official, often through a manager or a friend, and make an offer - or a threat. Then place the bet, usually at high odds, and collect.
In one case, a punter appeared holding a bag of cash at a Hong Kong betting shop, and wagered the lot on a South Korean football match. It was no surprise when the game turned out as he predicted.
"There's all sorts of things that can be done. It invariably comes with having some sort of in-road to the team, whether it's via a manager or via socially having some connection to the club," Ferguson said.
"The less conspicuous you can make it, so it can be put down to just being a normal part of the game, the more easy it is to get away with."
One target of the fixers seems to have been Jeong Jong-Kwan, a talented midfielder who once touched the heights of Asian football when he helped South Korea's Jeonbuk Motors win the 2006 AFC Champions League.
But Jeong had fallen on hard times. After serving jail time for avoiding military service, the 29-year-old was playing for third-tier Seoul United, his career on the slide.
On May 30, a hotel worker in Seoul's Apgujeong-dong district found Jeong hanging dead in his room, after an apparent suicide linked to a widespread fixing scam which has rocked Korean football.
"I'm ashamed of myself as a person involved in the match-fixing scandal," said a note near the body, according to media reports.
"Those under investigation are all my friends and they haven't blown my name because of friendship. All is my fault and I got them involved."
Jeong's death came among an unprecedented run of bad news for Korean soccer including the top-tier K-League, one of Asia's wealthiest and most successful football competitions.
Police were already probing match-fixing links in the suicide of Incheon United goalkeeper Yoon Ki-Won, who was found dead in his car with a half-burnt charcoal briquette and an envelope containing one million won ($930).
Last week the K-League responded by banning 10 accused players for life - the toughest penalty in its 28-year history - even before they had been found guilty. Eight of them are from the same K-League club, Daejeon Citizen.
"We made the decision, determined that this would be the first and the last match-fixing scandal in the league," said Kwak Young-Cheol, head of the K-League's disciplinary committee.
That is perhaps wishful thinking. After all, match-fixing has even hit England's super-rich Premier League, notably when a Malaysian syndicate was found to have tampered with floodlights at stadiums in the 1990s.
In 2005, German referee Robert Hoyzer was jailed for fixing matches including a first-round German Cup tie in which he sent off a striker and awarded the other team two dubious penalties.
And Italian giants Juventus were stripped of two Serie A titles and demoted in the 2006 "calciopoli" scandal which found several clubs tried to rig results by selecting compliant referees.
But Asian corruption is on another level. In China, the troubled Super League lost its title sponsor and national TV deal after rampant bribery and cheating, long suspected by fans, left several top officials facing trial.
Malaysia, where the Asian Football Confederation (AFC) is based, suffers from graft so pervasive officials warn it is "destroying" the sport, with gangs which have repeatedly been linked to scams in Europe.
Even Singapore's tiny S-League has suffered serious match-fixing problems, and a Singaporean man is now on trial for allegedly rigging matches in faraway Finland.
Thailand, Hong Kong and Vietnam have all battled major scandals, decimating local support and helping push fans towards European football, especially the wildly popular English Premier League.
"No (Asian) national league is free of corruption. Corruption is rife everywhere," said former AFC general secretary Peter Velappan, who said it was largely the fault of clubs which pay their players late or poorly.
"These guys they get married, they have family, they have a posh car, so who is going to pay for this?" Velappan said.
The problem stems partly from Asia's deep-set affinity with gambling, which has made football betting a multi-billion dollar industry in the region with huge sums to be won and lost.
It has also been fuelled by an explosion in betting options, many available online, which has made it possible for ordinary punters to put money on obscure games around the world.
"It's not necessarily the most obvious thing like fixing a match. Sometimes it's about who's leading at half-time or who scores first," Ferguson said.
"If you can get one team to lead at half-time and the other team to miraculously come back, the odds on that are far greater.
"(But) if you're someone who gets caught out by a Finnish team playing a Maltese team in a Champions League qualifier in the first week of July, well I'm afraid I don't have much sympathy," he added.
FIFA has vowed to clamp down on fixing, and has even teamed up with the international police agency Interpol to root out the syndicates. But graft allegations against top officials at the world body make such pledges ring hollow.
"Corruption is across the board at all levels" of football, said Velappan, who had a 30-year career at the AFC - whose president Mohamed bin Hammam is currently suspended over bribery claims.
"Let's give a clean, level field for the players to play," bin Hammam's stand-in, acting AFC president Zhang Jilong, told AFP this month. "Let's work together to make the football field as clean as it should be."
But Ferguson said official crackdowns are most probably doomed, mainly as match-fixing is often a cross-border crime - jumbling up different laws and jurisdictions - and firm evidence is hard to come by.
"Personally I'm a bit cynical," he said. "Any time there's a prize, there's potential for corruption. It's as simple as that."