The Herald on Sunday understands that at the 2014 tournament a group of British men were caught.
They were kicked out of the Auckland event, and one of their group - London-based Dan Dobson - was later arrested at the Australian Open after being spotted during a first-round match.
He was found to have an electronic device stitched into his shorts, enabling him to covertly communicate scores from courtside to allow his employers to beat the delays in the scoring provided by television coverage.
Dobson was charged with "engaging in conduct that would corrupt a betting outcome".
He was sending the outcome of each point to Sporting Data Limited, which used the information to make bets with online betting exchanges.
It was alleged that the company - and others who used courtsiders - could have up to a five-second advantage on punters who were betting on "old data".
The charges were later dropped by the Victoria Police, but courtsiding remains banned at all tennis tournaments.
The ATP and WTA employ a security team who cover the globe, scanning the stands for individuals who fit the profile: usually young European males, almost always alone, who are intently watching the action but not behaving like other fans.
They don't cheer or clap, don't interact with other patrons and rarely eat or drink.
Since the ATP and WTA employed their security unit in 2012, the Herald on Sunday understands that evictions for courtsiding have taken place between 100 and 200 times a year.
It's believed there were at least two individuals removed from Brisbane's tournament last week, and others were apparently nabbed courtsiding at the ATP tournament in Doha.
"It's something we won't tolerate," ASB Classic tournament director Karl Budge said.
"We work very closely with the tennis integrity unit, we have them here and they come and do training with our staff, everyone from the ushers through to our security team ... We have people here patrolling the venue looking for them. The WTA and ATP have a zero tolerance policy."
Because of their specialised skills, courtsiders often return to tournaments they have been ejected from. If they are caught again, they can theoretically be charged with trespassing, although this is a rare occurrence.
Courtsiding has been prevalent for more than a decade but has been banned since 2007, after the irregular scoring scandal, which former world No3 Nikolay Davydenko was allegedly linked to, came to public attention.