For as little as a half cent each click, websites hawk everything from LinkedIn connections to make members appear more employable to Soundcloud plays to influence record label interest.
"Anytime there's a monetary value added to clicks, there's going to be people going to the dark side," said Mitul Gandhi, CEO of seoClarity, a Des Plaines, Ill., social media marketing firm that weeds out phony online engagements.
Italian security researchers and bloggers Andrea Stroppa and Carla De Micheli estimated in 2013 that sales of fake Twitter followers have the potential to bring in $40 million to $360 million to date, and that fake Facebook activities bring in $200 million a year.
As a result, many firms, whose values are based on credibility, have entire teams doggedly pursuing the buyers and brokers of fake clicks. But each time they crack down on one, another, more creative scheme emerges.
When software engineers wrote computer programs, for example, to generate lucrative fake clicks, tech giants fought back with software that screens out "bot-generated" clicks and began regularly sweeping user accounts.
YouTube wiped out billions of music industry video views last December after auditors found some videos apparently had exaggerated numbers of views. Its parent-company, Google, is also constantly battling people who generate fake clicks on their ads.
And Facebook, whose most recent quarterly report estimated as many as 14.1 million of its 1.18 billion active users are fraudulent accounts, does frequent purges. That's particularly important for a company that was built on the principle that users are real people.
Twitter's Jim Prosser said there's no upside. "In the end, their accounts are suspended, they're out the money and they lose the followers," he said.
LinkedIn spokesman Doug Madey said buying connections "dilutes the member experience," violates their user agreement and can also prompt account closures.
Google and YouTube "take action against bad actors that seek to game our systems," said spokeswoman Andrea Faville.
Dhaka, Bangladesh, a city of 7 million in South Asia, is an international hub for click farms.
The CEO of Dhaka-based social media promotion firm Unique IT World said he has paid workers to manually click on clients' social media pages, making it harder for Facebook, Google and others to catch them. "Those accounts are not fake, they were genuine," Shaiful Islam said.
A recent check on Facebook showed Dhaka was the most popular city for many, including soccer star Leo Messi, who has 51 million likes; Facebook's own security page, which has 7.7 million likes; and Google's Facebook page, which has 15.2 million likes.
In 2013, the State Department, which has more than 400,000 likes and was recently most popular in Cairo, said it would stop buying Facebook fans after its inspector general criticized the agency for spending $630,000 to boost the numbers.
In one case, its fan tally rose from about 10,000 to more than 2.5 million.